The Definitive Guide To Cold Email Deliverability 2021

Lets break down the entire process of how to achieve the best possible deliverability for your cold email campaigns, from start to finish.

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Since its inception, email has been one of the most effective and direct ways for marketers to reach their target audience. It’s simple, effective, and relatively affordable for nearly any company big or small. The biggest issue facing this marketing strategy however, is actually being able to reach the primary inbox of your recipients. While it is easy enough to create an email address and start tossing out messages to an email list, there are multiple factors that are taken into account whenever you send out an email. It’s both a simple and complicated process, as it requires multiple systems and protocols to work in tandem in order to accomplish the basic task of delivering an email to a recipient.

In this article, we will break down the entire process of how to achieve the best possible deliverability for your email campaigns, from start to finish. Being the owners and founders of Warmup Inbox and Leadroot, we have been working within this space for over 2 years and have successfully sent more than 1 million cold emails for our clients. Over this time we have seen a lot of misconceptions and confusion around the best practices for deliverability, so we felt that it would be beneficial to everyone if we documented our knowledge into a single source for people to reference. Over the years we have performed hundreds of hours of research into the topic, as well as spend countless amounts of time and money experimenting to get to where we are today, so we want to make sure that others don’t repeat the same mistakes we have made in the past.

This article is intended to be aimed at those both new and experienced to organizing and executing cold email campaigns. This article is NOT aimed at those looking to send marketing emails, as this is a separate enough process from cold email that it would warrant its own article and we will not be touching upon it here.

This guide is Warmup Inboxes definitive guide, and will not cover absolutely every aspect of email deliverability. We do not know everything there is about deliverability and we probably never will, but this is what we know works based upon our experience. As time goes on we will continue to update this article based upon new information we learn, but at the time of writing these are all the criteria that we are aware of for determining inbox placement when performing cold email outreach, so let’s get started.

How Email Reputation Is Broken Down

 

Email reputation is a complicated metric that is difficult to determine due to a variety of reasons, the main one being that there is no definitive explanation of how internet and email service providers generate this score. Based on factors within our control, we know that this score is determined by the actions of an email address under a said domain. Who an email reaches out to, how they reach out to them, and what is contained within the email address are all considerations that ISP (internet service provider) and ESP (email service provider) look at when determining email reputation. Let’s break down everything that we are aware of that affects your reputation.

1. IP Reputation

IP Reputation is the most important factor for determining the overall deliverability of any given inbox under a domain. Whenever an email service provider is determining the placement of incoming messages, they will refer to the history of the IP address associated with the domain of the email as nearly all sending history is tied to this value. Anytime an email bounces, gets delivered, or gets sent to a spam folder, internet and email service providers take note and calculate a reputation score to assign to this IP address. This reputation score is then shared among other email and internet service providers in order to provide a reliable idea on how trustworthy a sender/IP address is before accepting any mail from it.

2. Domain Reputation

Domain Reputation is very similar to IP reputation, with the exception that all sender history under a specific domain is tied directly to the domain itself rather than the IP address. While it is typical for a domain to have the same IP address for the lifetime of its existence, this is not always the case as it is common for websites/domains with high amounts of traffic to have rotating/shared IP addresses in order to more reliably manage their sites. Domain reputation allows service providers to maintain a sender history based on the domain alone, without taking into account the IP address and its history.

3. Content Reputation

The content of the messages sent out from your domain/IP address is taken into consideration for determining your reputation. The type of language you use, including links and attachments, as well as the length and size of an email are all factors that spam filters, ISPs and ESP providers look at when determining the likelihood of an incoming message being spam or not.

The language used in emails can have a direct impact on reputation, as there are numerous words and phrases that are commonly used amongst those sending out spam messages. These words and phrases are typically referred to as Negative Keywords in this context, as many spam filters will specifically quarantine/deny emails that utilize too many of these words. Words and phrases such as “Free”, “Password” and “Bank Account” are enough to trigger a spam filter to direct your email to a spam folder, alongside other words that are typically associated with targeting individuals working within certain industries such as recruitment or technology.

Having too many links and attachments can also have a direct impact on your reputation as well, since this is another red flag that spam filters and ESP/ISP providers look at when sending out emails to previously uncontacted recipients. Email and internet service providers always prefer receiving emails in plain text, with little to no additional formatting or links/redirects to other websites and addresses. The sweet spot we have found is to only include 1 link within an email address and limit the total character count of an email address to around 500 characters, and avoid the use of any negative keywords that could potentially trigger a spam filter.

4. Inbox Reputation

Two inboxes under the same domain can perform differently during outreach. The exact details for this I cannot confirm but based upon our experience managing hundreds of email addresses for cold email outreach, ESP providers will maintain a separate sender score for each individual inbox under a domain. This reputation takes into account the quality of contacts it is reaching out to, the amount of engagement this inbox participates in with other email addresses, and the total sending volume of the inbox, alongside the quality of the messages that are being sent out under it.

5. Sending Volume

The total amount of mail sent out under your domain and IP address affect your reputation. Daily send volume as well as lifetime send volume are taken into consideration when determining your reputation. The reason why this is an important consideration is due to how high sending volumes are typically associated with spammers, where they will attempt to send out as many emails as possible before an inbox or domain gets shut down by an ISP or ESP provider. It is not normal behavior to send out thousands of emails a day to previously uncontacted email addresses, so these providers prefer inboxes that keep their sending volumes consistent and low.

 

Domain Infrastructure

Now that we have established what makes up a sender reputation, let's take a deeper look at how domains and DNS play a part in email deliverability. Outside of IP reputation, the composition and configuration of your DNS settings under a domain play a large part in determining if a receiving mail server will accept your mail or not. While ESP and ISP reputation is determined by your actions and content through email, your domain health is determined by the protocols and configuration of your DNS settings.

To give a bit of background, the Domain Name System (DNS) is used by internet based systems for mapping out alphabetic names to an IP address. Think of DNS like a phonebook, in that if you are attempting to reach a web server that contains a website you can simply navigate to it by entering in a domain name as opposed to entering in the actual IP address. DNS is also utilized for maintaining various types of records and important information regarding a domain, as DNS is responsible for handling various types of queries and requests related to internet traffic.

Let's break down exactly how the setup of a domain plays a role in email and what you can do to optimize your deliverability under a domain.

Separating Sending Domains From Primary Domains

Before I go into any more details regarding the importance of domain infrastructure, I want to stress the importance and benefits of creating separate domains for the sole purpose of performing email outreach. While a majority of the factors that play into high deliverability rates depend on the actions and preparations of the user and can easily be corrected or adjusted as needed, ISP and ESP reputation cannot be fixed as easily if a problem were to arise.

If you are performing any type of email outreach, it is a safe assumption that you have a website of some sort that you are attempting to direct recipients to or is the primary domain associated with your business or service. Being one of the more important (and valuable) assets a business can have, the domain name and associated website hosted under this domain should be held at the highest reputation level possible.

Performing any type of outreach underneath the primary domain of a company should be avoided for this reason, as there are too many unknown elements when performing email outreach that can cause lasting effects for your primary domain if you were to run into an unexpected issue.

For better or worse, ESP and ISP reputation will always be tied to an IP address and domain. As an example, if you were to perform outreach under your primary domain and inadvertently reached out to multiple spam traps or had a large percentage of your emails bounce during a campaign, this will have a permanent effect going forward for all future emails you send out from your primary domain.

By creating alternative domains for outreach you are effectively separating your primary domain's reputation from that of your outgoing emails, allowing you to perform outreach without the worry of having any reputation issues permanently tied to your primary domain. It is easier to build up a positive domain reputation under a brand new domain than it is to attempt and revive the reputation of a damaged or burned domain, so keep this in mind.

A misconception that I want to address at the tail end here is that of subdomains and how IP/Domain reputation works with them. Based upon our time interacting with our users as well as other professionals within the marketing space performing email outreach, we have seen a few people be confused as to why they are experiencing delivery issues when using a subdomain thinking that it is the same as utilizing a new domain. To be clear, subdomains inherit the reputation of its parent as all associations will resolve back to the primary host.

SPF, DKIM, and DMARC

If you have ever bought a domain and set up an email address under it, you will most likely be familiar with terms such as SPF, DKIM, and DMARC. These three email security protocols are mentioned frequently in relation to email deliverability because they play an important role in verifying the identity of incoming and outgoing mail. In the past we have covered what SPF, DKIM, and DMARC is, so let’s explore how having these security protocols in place helps with deliverability in general.

Whenever you attempt to make contact with another email address under an email service provider, the receiving mail server needs to confirm the identity of the sender before being able to accept it. The methods used to identify the identity of the email sender are SPF, DKIM, and DMARC.

So if you are sending out an email from your own email account and mail server, why do we need to verify our identities using these protocols? The reason for this is due to spammers and hackers, and the possible ways in which some people will go about performing their spam techniques or scams. These security protocols primarily protect mail servers from accepting spoofed messages, where a spammer will send an email disguised as an authentic sender in the hopes that it will be treated as a normal email by the recipient in order to get their message/phishing scheme through spam filters that normally would block this type of traffic.

SPF, DKIM, and DMARC specifically prevent this type of behavior from occurring under the given domain and email server configured with these security protocols. Sender Policy Framework (SPF) enables receiving mail servers to confirm if they have successful sent an email, DomainKey Identified Mail (DKIM) gives all emails an encrypted signature as a way to verify that a message hasn’t been compromised between being sent and delivered (Think of DKIM as an MD5 checksum for email messages), and Domain-based Message Authentication, Reporting & Conformance (DMARC) defines what email authentication methods are being used under a given mail server and provides instructions on how to proceed if any authentication checks fail.

These 3 security protocols are critical for deliverability because nearly all mail servers are looking for these valid records under your DNS settings when determining if they should accept a message or not. It is not uncommon for companies and individuals to set up their mail filters to deny incoming mail that is missing any of these protocols, so for this alone it should be the first priority after registering a domain + email workplace to get setup with this.

Any domain you are utilizing should have all 3 of these security protocols in place before you begin any type of outreach, no matter what.

Valid Website Redirects

I want to clarify at the start of this section that having a valid website or website redirect under a domain responsible for outreach email is NOT necessary for achieving maximum deliverability. Syntax wise, there is absolutely no need to set up a redirect or website under a domain/IP address that is only a response for sending out mail. The reason why this section of the article exists is due to the human factor of email marketing, and the manner in which recipients respond/engage with your outreach emails.

To put it bluntly, having your sender domain redirect to your primary company domain will help add legitimacy to your emails. It looks suspicious when you receive an email from an unknown person and their associated domain leads to a 404 page, you want recipients of your emails to not have any doubt about the legitimacy of your outreach.

Website redirects can be set up in a few different ways, the manner in which you execute a redirect does not matter as the end user will not be able to tell either way.

- 301 Redirect - This refers to a permanent redirect of one domain to another IP address that is hosting another domain and website. Setting up a permanent redirect has SEO benefits as it essentially locks in the domain you setup a 301 redirect under to another domain

- 302 Redirect - This refers to a temporary page redirect. For the purpose of email outreach and setting up sending domains, these types of redirects should be avoided unless you have plans in the future to point a sending domain to another website. 302 redirects don’t have any benefit for SEO since this essentially lets search engines know that this domain is not going to permanently point towards the current website.

Whichever type of redirect makes the most sense for you to choose, it goes a long way to set this up since it can make or break a positive reply to your outreach.

Domain Age

Domain age is a factor used by ESP and ISP providers when determining the trustworthiness of an incoming email. The reasoning behind this, is that one of the various methods spammers use to send out massive amounts of emails a minute is to register and sign up multiple domains at a time in order to reach as many people as possible before their accounts get disabled/permanently blacklisted. 

While being cautious with new domains is effective at preventing and reducing spammers, it can be a cause for issue among those who are performing general email outreach due to the nature of how people manage cold email outreach in modern times.

The general rule of thumb that we’ve seen being spread around by people is that the older a domain is, the more trustworthy it is. In general this rule holds true since older domains are seen as more trustworthy by ESP and ISP providers, but this phrase can be a bit misleading because based on our experiences utilizing older domains and hearing from our own clients regarding their use of older domains, it can be more cause for headache depending on how old the domain is and how much sending history is tied to it.

For this reason, we typically will suggest people to be cautious when utilizing an older domain they own for outreach purposes as it is typically safer to utilize a domain with about a month or so of age under its belt. This doesn’t always hold true, but if you are utilizing an older domain and notice higher than average spam/bounce rates (Anything more than 5% is cause for concern, most email automation tools will keep track of these metrics), I would start transitioning your campaign to a new domain so as to avoid wasting any contact emails.

Since older domains can have a bit of an unknown element to them, we personally will avoid utilizing existing domains all together and simply register new domains, set them up for outreach, and leave them warming at low daily send volumes until we are ready to start our campaigns. By doing this, it allows us to build up age on our domains while also building up an extensive history of positive email engagement and helps ensure that we have the best deliverability chance possible out of the gate.

Reserve Domains/Inboxes

While we can set up and prepare our domains perfectly, email outreach can still be unpredictable at times due to the nature of sending out emails to recipients you have never had contact with before. Emails can bounce, domains can get burned over time, recipients of your emails can report you as spam to their ESP provider, the list goes on and on for how a sending domain can be ruined and rendered useless for outreach purposes.

To compensate for any unexpected issues during an email campaign, what we will do is buy and set up additional domains and email addresses that we will keep warmed alongside our domains that are in use for an email campaign. If a problem should arise with any of our actively sending domains, such as higher than acceptable spam rates, delivery issues, or getting blacklisted/disabled, we can then simply swap out the bad domain and email addresses for our already prepped email addresses under separate domains and get our outreach back on track almost immediately.

While buying additional domains and setting up additional ESP providers under these domains adds to the overall costs of managing an email campaign, it adds an additional layer of security to your efforts so that the rest of the time and effort put into setting up a campaign isn’t wasted if a domain gets burned.

Think of doing this as a form of insurance, you hope you do not need to utilize these additional domains but in the chance that you are running into deliverability issues, you will be happy to have them.

 

Blacklist Overview

We’ve established how important it is to have the proper security protocols in place under a sending domain, let’s take a quicker look at blacklists and how exactly they work in relation to email deliverability.

So what even is a blacklist? In order to keep track of domains and IP addresses that are causing problems for other people, ESP and ISP providers use a variety of tools and methods for determining the likelihood that an incoming message is spam or not. One of the most common ways that the internet in general keeps track of these bad actors are through remote blacklists (RBL). 

There are more than a thousand RBL’s currently active and in use at the time of writing. Some of these lists are maintained by email service providers and internet service providers, while others are maintained publicly by businesses within the technology industry or are fully open source projects run by volunteers.

So how exactly do normal people end up on these blacklists if they are exclusively meant to combat spammers? Unfortunately due to the nature of email marketing, it can be difficult sometimes for these systems to correctly identify who is a spammer and who is simply performing email marketing.

Recipients can also be responsible for landing you on a black list if they report your emails as spam. Whenever you hit the Junk or Spam button under your mail client on an unwanted email, your ESP provider takes note as this manual action by recipients plays a role in determining your reputation within their system. Over time if you get enough of these reports, your ESP provider will then either submit you to one of their own blacklists, or share this negative history with other blacklist providers in order to keep others aware of potential abuse if they are to accept mail from the problematic domain. Recipients can also manually submit you to a blacklist if they feel it necessary, so keep this in mind as you craft your email drafts for an outreach campaign as some people will do this if they feel that you are being deceptive and spammy with your pitch.

I also want to touch on the different types of blacklists that exist within this section of the article. From interactions with our clients and general interactions with others within the marketing space, I’ve experienced quite a few people that have been confused about blacklist placement they have experienced in the past.

Blacklists are organized into 2 primary categories, IP based blacklists and domain based blacklists. For the purpose of this article I'm going to skip over talking about why blacklists are separated into these 2 separate categories because the logistics do not matter for this topic but I wanted to acknowledge this if readers wish to read further into the subject on their own. What does matter is being able to identify which type of blacklist a domain or mail server is currently on and knowing the source of how it has occurred.

The main categories of blacklists that have an affect on email deliverability from our experience are

 
​1. New Domain Blacklists - This category applies to blacklists such as Sem Fresh, where a newly registered domain under a domain provider will automatically be added to a blacklist for around 7-14 days after creation. These blacklists are intended to prevent spammers from mass creating new domains to utilize for email blasts
2. Spam Trap Blacklists - As a way of detecting when people are sending out mass amounts of spam mail, ESP providers will take email addresses that have been abandoned for a certain duration of time and set it up as a spam trap. If anyone attempts to reach out to this particular long dormant email address, they automatically get added to a specific blacklist for those who fall into spam traps, since realistically if this email address was abandoned with no activity or use in years, it is suspicious to attempt contact with it. These types of blacklists are generally easy to avoid, as only those who are selling old email lists will have an address that has been converted into a spam trap.
3. Phishing/Ransomware Blacklists - If any domain or IP is caught sending any type of email intended to harvest/steal personal information of any kind, they will typically be added to specific blacklists for this. Most domains or IP addresses will have a hard time getting off these types of lists, since these are the most destructive types of emails to users in general.
4. Spam Blacklists - If you are performing email marketing for long enough, you will most likely have a domain end up on a general spam blacklist over time as they are the most common type of blacklists to be on.

For obvious reasons, you do not want to be on any blacklist. They are associated with negative and malicious emails and a majority of spam filters will outright block emails from domains on a blacklist so as soon as you find out that you have landed on a blacklist, you should attempt to delist as soon as possible. An important thing to note about delisting is that just because you get off a blacklist once, does not mean that you cannot end up there again. Whenever you end up on a blacklist, it is important to audit your email copy, recipients, and the manner in which you are acquiring your outreach data to ensure that it will not come back to haunt you in the future.

Shared IP Addresses

One of the more common reasons why people suffer poor deliverability rates with outreach campaigns is due to their sending domain being associated with a black list. An IP address can get added to a black list for a variety of reasons, primarily being related to the activity that is occurring in association with the IP address/domain, but this is not always the case.

Whenever you register a domain through a registration provider or sign up for an email service provider such as Google or Microsoft, you are initially given an IP address that is shared by other users of the service. These types of IP addresses are known as “Shared IP’s”, since you are sharing these addresses with other unknown users of the service.

In most circumstances, there is nothing wrong with having your domain and mail server hosted under a shared IP. The problems that can occur from being under a shared IP address are more a result of bad luck than the practice of shared IP’s themselves. When signing up for any shared service, you are randomly assigned an IP address from a random pool of other IP’s that the provider controls. If a user under a shared IP ends up on a blacklist due to email abuse or any other email related abuse, all IP’s under that given pool will also end up on that blacklist as a majority of organizations managing blacklists will keep track of spammers via IP addresses. If you have ever registered a new domain and noticed that you were already on a blacklist before even setting up your email, chances are it is because of being under a bad shared IP range.

So what do you do if you register a domain or sign up for an ESP and your assigned IP address is on a blacklist? Unfortunately, there is not much you can do on your end as the provider you signed up with needs to handle this on their end as they are the ones responsible for managing this. If you write to them and show them that you are under a bad IP, they should be able to correct this for you.

We do NOT recommend utilizing a domain for outreach if it's currently on a banned IP range, especially for cold email. You are limiting your ability to reach the maximum number of people possible if you start performing research under a domain on a blacklist, it's essentially like trying to win a footrace with your legs tied together. If you registered a domain and its under a banned IP Range, contact your domain provider as soon as possible so that they can either move your domain to a non-blacklisted IP range or perform the delisting process for the IP range your current domain is under.

The Inbox Infrastructure

 

Now that we have gone over what you need to take into consideration when creating, utilizing, and preparing domains for cold email outreach, let's take a deeper look at how exactly we structure our email campaigns and what preparations we take in order for our outreach to go smoothly for as long as we need it too.

This section is going to cover a lot of smaller details that I’ve seen people gloss over with their own campaigns, so I wanted to go into more detail regarding certain actions you can take in order to make your inboxes look and feel more authentic when performing outreach.

In general, most people do not like being on the receiving end of a cold email campaign since it insinuates that someone unknown to them has obtained their email address and is being used for unsolicited contact. While most people can easily identify when they receive a cold email from a sending campaign based upon the email copy and nature of the pitch, there are a lot of small things you can do that will add legitimacy to your email addresses and make people feel less like they are being arbitrarily targeted for an outreach campaign.

Email Avatars & Persona's

When performing cold email outreach, the best approach we have found when creating and setting up email addresses is to model them exactly the same way you would any other professional email address that would be used by a real person. More specifically, what we recommend companies do is to create their outreach email addresses after existing employees (with their permission of course).

The reason for doing this as opposed to making up a fake person is that it adds an additional layer of authenticity to your outreach emails. If you receive a cold email from a person you have never had contact with, one of the first things people will do to determine who they are is a simple Google search of their name or email address. When an outreach email address shares the basic information of an existing member of your team and your email copy is related to the business you are performing outreach for, it will be easier for people to determine that this email is authentic and not spam.

For all email addresses you plan on utilizing for outreach, one of the first things you should get set up right away is the signature for all inboxes. As I stated before, the information you present for signatures should be consistent with that of the avatar you are modeling these email addresses off of, but there is one thing that you should include here no matter which mail sending service you are utilizing for outreach.

Unsubscribe links are exactly what they sound like, they are links that recipients can use to unsubscribe from any further outreach from you. If you are based in the USA or are sending outreach to US based recipients, the US’s CAN-SPAM legislation requires all companies to provide a way for users to tell them to stop sending them any further outreach. Due to the nature of cold email outreach, you absolutely need and should include these links alongside the other information contained within an email's signature to ensure that all outreach you perform under a given domain/inbox is compliant with US law.

While it is perfectly fine to create a fake persona for your email outreach, we have found that this is less effective than just associating a real name and picture to the content you are sending out to people.

Inboxes Per Domain

So you set up your sending domains and gathered together the required information and materials to start getting your sending email addresses setup, but how many email addresses should you be utilizing per domain for outreach? This question might not seem to make sense at first, because in most other cases for a company you only need to have a domain and a mail server, then you can create as many email addresses as you need and use them without a problem. For sending domains and cold email outreach however, this approach can result in issues that can end up ruining an entire campaign if something were to go wrong.

To keep things simple, we will only create and utilize 1-3 email addresses per domain. We do this for two primary reasons.

1. Only having 1-3 email addresses per domain means that it is very difficult for us to reach daily send volumes limits, or get close to sending volumes that could result in issues for the domain.
2. Having a hard rule on 1-3 email addresses per domain means that if we need to scale up our outreach, we are not putting all our dependence on a single domain, even for small outreach campaigns

Based on past experiences, we never ran into any direct issues related to multiple emails under a domain but we’ve found this approach to have too much potential for issues to be worth it. For the sake of consistency and the overall success of a campaign, we don’t recommend utilizing more than 3 email addresses per domain.

Inboxes Per Domain

So you set up your sending domains and gathered together the required information and materials to start getting your sending email addresses setup, but how many email addresses should you be utilizing per domain for outreach? This question might not seem to make sense at first, because in most other cases for a company you only need to have a domain and a mail server, then you can create as many email addresses as you need and use them without a problem. For sending domains and cold email outreach however, this approach can result in issues that can end up ruining an entire campaign if something were to go wrong.

To keep things simple, we will only create and utilize 1-3 email addresses per domain. We do this for two primary reasons.

1. Only having 1-3 email addresses per domain means that it is very difficult for us to reach daily send volumes limits, or get close to sending volumes that could result in issues for the domain.
2. Having a hard rule on 1-3 email addresses per domain means that if we need to scale up our outreach, we are not putting all our dependence on a single domain, even for small outreach campaigns

Based on past experiences, we never ran into any direct issues related to multiple emails under a domain but we’ve found this approach to have too much potential for issues to be worth it. For the sake of consistency and the overall success of a campaign, we don’t recommend utilizing more than 3 email addresses per domain.

 

Warmup Process

So you set up your sending domains and created your associated email addresses, what should your next steps be? At Warmup Inbox for our own outreach campaigns, once our inboxes are created and our domain infrastructure is set up and working correctly we go on to start the warming period of our outreach preparations, where we connect all our newly created inboxes to our warming tool Warmup Inbox and just leave them to warm until we are ready to launch our campaigns.

But what even is warming anyways and why do we bother doing this instead of trying to get our outreach campaigns started as soon as possible? The most simple answer is that...

1. It helps maximize our chances of deliverability
2. It helps prevent our outreach from ending up the in the spam folder of our recipients
3. It keeps the IP reputation of our domains high
4. It helps us identify if we are having any placement/delivery issues with a domain before making first contact with anyone on our email list.

These are all the primary reasons why we highly stress to users of our tool that it is important to constantly be warming your sending domains in order to build up and maintain high reputation and deliverability rates.

The amount of time we recommend to users for how long they should warm their inboxes before beginning outreach is between 45 and 90 days. This is obviously a large amount of time to wait between preparing and beginning an outreach campaign, but since developing this tool for our own in-house use we have found this 45-90 day gap to be the sweet spot, where deliverability/spam rates don’t seem to improve noticeably after this amount of time warming.

While it isn’t necessary to warm your outreach inboxes for this long, we strongly stress that those performing cold email outreach should always be warming their domains and inboxes for as long as you plan on utilizing these accounts for outreach, as otherwise you are potentially missing out on opportunities if your deliverability rates suffer during a campaign.

Email Copy

 

We’ve gone into detail regarding all the factors and steps you should be taking in order to maximize your deliverability potential, so let's take a closer look at how the actual message of your emails affect deliverability and inbox placement. While the majority of factors that determine placement involve your DNS settings and reputation among ESP and ISP providers, the type of message you are sending out to contacts can make or break the success of your email campaigns.

One of the many things I've noticed from receiving cold emails or reading through the various other articles outlining cold email practices is that many people will commonly utilize negative keywords that are commonly used by spammers and not touch upon or realize why this is a bad practice to engage in. Negative keywords are words or phrases that are almost universally recognized as being related to spam, phishing, or solicitation emails, and these types of words or phrases are bad to use for this reason. Spam filters pay attention to the language within the contents of an email, and if there are either too many negative keywords or phrases that are commonly associated with spammers, they can and typically will bucket your outreach efforts as spam and direct your mail into this folder.

So what exactly are negative keywords and is there a list of these terms to avoid using? Unfortunately there is not one definitive list of negative keywords to use as reference, but thankfully through trial and error there are lists that exist online that lay out the general terminology to avoid if you want to maximize your deliverability rates. In general you can pick up on the type of language that you should avoid using when you explore these lists and see the type of words that spam filters have issues with. We have a list of all the most commonly known negative keywords in this article, but this list is by no means the definitive negative keyword list since without insider knowledge of how ESP providers manage these lists, we can only go by what negative keywords we know are associated with spammers.

In tandem with negative keywords, I also want to touch upon the manner in which you word and approach your cold emails. While the industry and reason for outreach will vary among those performing outreach, you should always avoid wording your email copies in ways that can come off as spam or junk mail. Recipients are very quick to pick up on messages that aren’t authentic and abuse or misuse common marketing talking points to try and convince their audience to engage with their outreach, but the best way that we personally have found to pursue outreach is to be straight to the point regarding

1. Who you are, what company you are/represent, and why you are reaching out to them
2. What you are offering
3. Convincing talking points regarding why your offering is worthwhile for the recipient to pursue further.
4. A direct call to action regarding how to proceed further if interested

It’s not worth it to pretend like your cold emails are being personally sent by the identity of the email address, most professionals understand the nature of cold emails and what they are, and can identify them when they are received. This is why you should be precise and short with your email copies and have a direct call to action so those interested can act on your email immediately. By doing this, it helps you to avoid the use of a majority of negative keywords as well as keep the total length of your emails short.

The benefit of keeping your outreach emails short is that it makes it more likely that recipients will actually read through the entire thing as opposed to just glancing at the content. My general rule of thumb is that if you need to scroll to read the full length of your email, it's too long so try to avoid anything that surpasses 250 words or so.

Another factor of your email copy that you should take careful consideration of is what you choose to utilize as the subject line of your emails. Being the first thing a recipient will read when you successfully send them an email, you want to make sure that it's short, direct, and clear regarding what it is you are reaching out to them about. Also keep in note that some of your recipients will most likely be reading this email + subject line off a phone, so keep in mind that length is important.

The general rule of thumb for a subject line is to keep it under 80 characters, this is around the max character limit that gets displayed on mobile devices for email clients.

The Contacts

 

While your inboxes are warming and getting prepared for outreach, it is a good time to begin getting together the contacts you plan on utilizing for your future campaigns. For obvious reasons this is one of the most critical aspects of a cold email campaign since the list of email addresses you load into an outreach tool should match your target audience for your campaign. It takes a while to get fully set up for a cold email campaign, if you are not spending the necessary time to target the correct people for the intended end goal you hope to achieve, you might as well not bother performing outreach at all.

So how do you go about getting hold of a list of email addresses? There are a wide variety of ways to go about this, I am only going to be covering the methods that I have found to be the most effective and efficient over the years, since other techniques are mostly a waste of time, effort, and resources unless you are targeting an extremely specific target audience.

The primary method of getting a hold of contacts is through...

1. Purchasing a lead list via a lead generation agency or platform
2. Developing an in house lead generation funnel for gathering targeted leads.

Purchasing lead lists is typically the most effective way of getting hold of the necessary leads for an outreach campaign, but comes at a premium cost. There are a multitude of lead generation agencies that provide this type of service, where they will perform all the leg work of performing lead research on your behalf for your target industry and recipients. They also typically will provide additional information as well that you can utilize to personalize your email copy a bit more to stand out. Overall if your end goal of performing cold email outreach is to grow your customer base and there is a direct return on investment for this activity, the time saving aspect of going through an agency is typically the best approach.

The other option that may make more sense to companies and individuals operating in more specific industries is to set up and manage an active lead generation funnel for obtaining the contact information of those who are more than likely to have an interest in your offerings.

So what exactly is a lead generation funnel? In general this term refers to the process of isolating and sorting out promising prospects from a wider audience. This can be done through a variety of different approaches, typically companies will utilize lead funnel approaches on landing pages or business websites in order to find qualified prospects from general web traffic. If your company is already utilizing such an approach, you should be utilizing these contacts for this if it makes sense for the industry you are targeting.

In terms of acquiring ideal leads for an outreach campaign, lead funnels are almost always the best approach for two main reasons.

1. The leads acquired through a leads funnel are more than likely already interested enough in your business to pursue things further
2. If you are obtaining these leads via newsletter signups or email registration offerings, these email addresses will be double opt-in addresses. In general double opt-in addresses have higher deliverability and conversion rates, so these are valuable.

One aspect of purchasing a lead list that you should absolutely avoid are businesses or individuals selling generic email lists. Typically these will be separated by industry, area, and various other related group tags, and cost much less than going through an agency for a lead list. The primary reason why you should avoid these lists is that in most cases, they will be garbage and you will end up wasting time and effort attempting to reach out to these individuals on this list. Another big factor against these preassembled lead lists is that the contacts found on these lists typically aren’t of good quality.

If an individual is selling a list to as many people as they can, more than likely this means that there currently are, or has already been multiple companies and individuals who have attempted contact with them. Even if this isn’t the case, there is little to no guarantee that these leads are ‘fresh’ in any way, meaning that it is possible that this contact information could be months, if not years old. From our experience managing campaigns, I would recommend only purchasing leads from reputable companies and sources as opposed to trying to save money at this stage, since it can end up causing more problems down the road.

Lead List Verification

I cannot stress enough how important it is to always verify each and every email address using a verification tool before attempting any cold email outreach. The reason for this is straightforward: any and all hard bounces that occur under your sending domain will have an effect on your IP/Domain reputation. The easiest way to avoid these bounces is to run your list of emails through a tool such as Neverbounce or Verifalia. These tools will highlight which emails are good, bad, or potentially bad so that you can weed out all the emails that come with the highest probability of bouncing.

So you run your list through an email verification service and it spits out a bunch of verification classifications for each of your contacts, what do they all mean? Each service will label these classifications differently, but they can typically be broken down into these 4 categories.

1. Valid
2. Invalid/Nonexistent
3. Catch All
4. Unknown

Valid emails are exactly as the name suggests, an email marked valid was confirmed to be an email address that exists under the associated domain’s mail server and is safe to email.

Invalid/Nonexistent email addresses are emails that have been confirmed to not exist under the given mail server associated with the domain of the email address.

When an email is labeled as “Catch-All”, this is a reference to the configuration of the mail server that is associated with the domain, where the configuration of said mail server is set up in a way to accept all emails that are sent towards it. This configuration exists primarily to catch email addresses that may have been sent to the wrong email address, or individuals attempting to send an email to a specific person but accidentally misspell the email address and hit send. A Catch All mail server will take any and all mail that isn’t directed at an existing email address, and direct it towards a single inbox that will then sort/process the email accordingly. These email addresses are a gamble to reach out too, since if the actual email address you are attempting to contact does not exist, your outreach will be directed to an entirely separate inbox that most likely will not try to engage back with you.

Unknown email addresses are essentially as the name implies, they are email addresses that an email verification service cannot confirm the existence of. In most circumstances, you should treat any emails labeled as “Unknown” as spam due to the unpredictability of attempting contact with them. In most cases, an email address coming up as Unknown is associated with a mail server that has Tarpitting or Greylisting enabled under it, which are additional security measures that a mail server can take to prevent spam mail from reaching their inboxes. This means that these email addresses potentially do exist, but is still a risky move to include them within your final email list.

For our own campaigns, we will entirely remove any email addresses that come up as Invalid or Unknown and only utilize email addresses that verify as Valid or Catch All. The primary reason why we also include catch-all email addresses in our list is that in most circumstances they will send correctly and not bounce back since they are being delivered to an inbox, but due to the nature of catch-all email servers we do not know for certain unless we receive a positive or negative reply back from said email address. We have found the risk of reaching out to these inboxes to be worth it, since it is commonplace for larger businesses to configure their mail servers in such a way to accept all incoming emails regardless of the receiving email address existing or not.

Handling Responses

 

So your campaign is live and you are running multiple outreach inboxes at the same time, sending out emails to hundreds or thousands of people a day. How do you efficiently and effectively handle all the responses that will be coming in? I’ll be going over a few ways that we have found to be effective for monitoring dozens/hundreds of inboxes at the same time.

There are three primary ways in which we will monitor our live email campaigns. Depending on the circumstance and the amount of inboxes we have running at a given time, we will generally rotate among these 2 methods. Depending on the size of your company and the type of outreach you are performing, these methods might not be very effective but these are the methods we have found to be the most effective for our manner of management. These methods are...

1. Manually monitoring responses within browser windows
2. Utilizing a customer communication tool/mass email client to sync all inboxes to the same space.

Manually monitoring email addresses within a browser seems inefficient, and it is if you are keeping track of more than 10+ email addresses, but I wanted to cover this method simply because there is no additional cost to your outreach budget for keeping track of campaigns in this manner. If we are only utilizing around 1 or 2 domains for a campaign this is the way we typically manage campaigns due to it not involving any setup or prep.

Customer communication tools are services that simply allow you to connect multiple inboxes to a single, primary view such as Front. This is the ideal solution for monitoring multiple inboxes during a live campaign, but this convenience typically will come at a premium as these services can get pricey quickly if you need to connect more than a handful of inboxes at the same time. In most cases the price is worth it as it allows multiple team members. There are free alternatives such as Mozilla’s Thunderbird email client that allows you to connect as many inboxes as you want for free, but their interface can be a bit clunky and outdated if you are not familiar with the interface. 

However you choose to manage your inboxes, it's important to be keeping tabs on responses hourly, since waiting too long to respond to any positive engagement can make or break a potential sale.

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