How to Avoid Landing In Spam:
Complete Guide 2021

For any email marketer, the biggest worry that comes from organizing and launching an email outreach campaign is the spam folder. When you are attempting to grow your brand, your business, and your audience through an email outreach campaign, the spam filter is the biggest hurdle that gets in the way of you reaching your target audience. While it does seem like spam filters only get in the way of you sending out your normal emails, it serves a critical purpose for maintaining healthy inboxes across the internet, blocking and filtering out millions of malicious or useless emails daily so that you don’t have to deal with your inbox being filled up with nonsense. 


While a majority of the emails that spam filters block out are actually spam or malicious messages, a small percentage of these blocked messages are normal emails sent by email marketers.  So how do normal emails end up getting flagged as spam and how can we avoid this for the future? In this article we will go over all of the known variables that can land your normal outreach emails into a recipient's spam folder.  We will also go over some best practices for avoiding hitting the spam folder in the future.

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Why Do My Emails Land In Spam To Begin With?

Whenever a mail server receives a piece of mail from an external source, it will examine various aspects of the email address. The aspects examined are it’s associated domain, the content of the email itself, and the content of the message body, as well as the email header. When these systems are analyzing a recipient, they are also taking into consideration past sender activity and reputation that gets shared among ESP and ISP providers in order to maintain a healthy sending network for the internet. If anything looks off, doesn’t line up, or seems suspicious based upon the processes performed by a mail server, then there is a high likelihood that an incoming piece of mail will be placed within the spam folder of a recipient, or outright blocked with a variant of an SMTP 550 error on the end of the recipient.


So what exactly looks suspicious to spam filters? In general, spam filters are looking for consistent patterns that line up with the behaviors of known spammers and the activities in which they engage in. Writing deceptive email copies, sending out large volume email blasts to seemingly random and unrelated contacts, utilizing free/new email addresses, and being previously reported for spamming activities are all habits that these systems look out for.

Overall, the main factors that land you in the spam folder as a sender are...


  1. Having a low IP/sender reputation

  2. Sending poor email content containing negative keywords

  3. Having DNS issues relating to your sender domain (including failed email authentication due to inpromper SPF/DKIM records)

  4. Having high spam complaints

  5. Having low engagement rates

  6. Being on a blacklist

If any of these factors are off in any way, it can be enough to instantly have ESP providers and spam filters move your outreach efforts into the spam folder.

What Is Deliverability & Why Is It Important?

So, now we know what will land you in the spam folder of a recipient. That is always an important factor to consider when preparing for an outreach campaign, but what exactly does the term deliverability mean, and why is that important to keep in mind during the preparations for an outreach campaign?


Email deliverability is the term used to describe the rate at which you land in the primary folder of a recipient's inbox. The primary folder of an inbox is simply the main inbox in which all mail is sorted into, typically by the time of delivery. The reason why you want to land in the primary inbox of a recipient is because this is the first thing we all see whenever we go to check our emails throughout the day. It’s the first thing we see when we log into an email account, the first thing we see when we go to load up any previous emails, and the first thing we see whenever we are checking to see if anything new has come in. 


If you want high engagement, reply, and open rates, you absolutely need to prioritize high deliverability rates or else your efforts will be wasted and left to rot in the spam folder of your recipients. So what determines the likelihood that your outreach will land in the primary folder of a recipient? 


There are a multitude of factors that influence this, much in the same way that there are multiple ways in which a spam filter can outright block your outreach. The main determining factors are:


  1. Your sender reputation score at the time of email delivery 

    • Overall reputation and ESP specific reputation both matter here

  2. Low spam complaint rates under the sender domain

  3. Low bounce rates under the sender domain

  4. The message content of the email itself 

    • Avoiding using negative keywords in your email

  5. Little to no blacklist presence under sender domain

  6. Having the proper security protocols + DNS records in place under sender domain 

    • SPF, DKIM, DMARC set up properly 

  7. Good email engagement rates under sender domain

    • It’s important to have a history of your past outreach efforts being opened, read, and engaged with after delivery


In general, as long as you are engaging in safe and healthy email practices under a sender domain with no prior history of reputation or delivery issues, your outreach emails will be delivered to the primary inbox of your recipient.

How Can I Avoid Landing In Spam?

If you start to notice your spam rates increasing at a noticeable rate while in the middle of an outreach campaign, this is typically an indication that something has changed in regards to either your sender reputation or the DNS of your sender domain, assuming that you have not changed anything involving your sending volume or email copy. 


A rise in spam rates can also be due to the nature of cold email in general.  Cold email is the act of sending emails out to previously uncontacted email addresses, which can be unpredictable at times, even when strictly utilizing fully verified and valid email addresses that have been run through reputable email verification services. If you have a list of 1,000 email addresses from contacts that fit your industry and employee title target, the first 500 emails are not guaranteed to produce the same deliverability results as the last 500 emails.


When it comes to rising spam rates, you should treat every situation the same.  Even if it’s due to a bad luck of the draw with an email list, every email lost to a spam folder could be a loss in a possible sale, conversion, or any other end goal you set out to achieve throughout the lifetime of an outreach campaign. 


Some of the first steps you should take to narrow down the list of possible causes for higher spam rates are:

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1. Check The Health Of Your Sender Domain’s DNS

This is one of the most straightforward ways of determining if anything has gone wrong with a sender domain. Whenever you set up a domain, for any purpose outside of just utilizing it as a sender domain, there are certain DNS records that need to be put in place for various reasons. Setting up website redirects, having A Records point to host IP addresses, adding MX records so that you can connect an email workspace, and setting up SPF, DKIM, and DMARC for said workspace are all common reasons why owners of sender domains will make adjustments to their DNS. 


In general, once you set these records up, you are finished.  Keep in mind, during the setup process, it is very easy to overlook some aspects that can cause issues for your deliverability.  It can sometimes take hours for changes to your DNS to fully propagate when you are in the middle of the setup process since you are unable to verify everything is set up properly once you are finished.  Domains can also break if a lookup specified in a DNS record is no longer valid or if your domain registration expires, so keep note of this if you are running into deliverability issues.  

The most straightforward way of checking the health of your sender domain is to run your domain through a tool like MxToolBox’s Health Check Lookup tool, which will perform dozens of tests on various aspects of your domains DNS in order to determine the overall email health rating of your sender domain. This will highlight any serious issues for your sender domain, as well as throw out any warnings or suggestions on specific DNS settings that you may want to adjust to line up with the standard syntax or best practice recommendations.


Once you know what is wrong with your DNS, you can take the necessary steps to repair whatever issues may be present, and in turn help deliverability overall.


2. Check Your Sender Domain Against a Blacklist Lookup Tool

Having a sender domain present on a blacklist can be one of the more common reasons as to why you are landing in spam folders.  Depending on the ESP provider and spam filters in place under a mail server, just simply being on any of the 100 most common blacklists on the internet is enough to ruin your attempts at outreach and land in the spam folder, so it’s important to act immediately once you are aware that you are on a blacklist.


I’ve covered the process of getting listed on a blacklist in previous posts i’ve written, so to give a simple summary, a sender domain will end up on a blacklist if it: 


  1. Receives too many spam complaints and your parent ESP provider submits your domain’s IP address to the appropriate blacklist.

  2. Bounces too many emails and your parent ESP provider submits your domain’s IP address to the appropriate blacklist.

  3. Sends too many emails to dormant email addresses or have extremely low engagement rates under a sender domain

  4. Sends an email to a spam trap/honeypot.

  5. Performs extremely high sending volumes/email blasts


A general rule of thumb to take into consideration when performing any type of email outreach is  if you are pushing the limits of an email service or are engaging in activities that can be interpreted as spam, it can land you on a blacklist.  As a result, this will cause you to land in spam more often due to spam filters and force receiving mail servers to be more cautious when accepting mail from such a domain.


The most straightforward way of checking to see if your sender domain is affected by a blacklist is to simply run your sender domain/mail servers IP address through a blacklist checking tool. Many of these tools exist online and generally perform the same task, but my suggestion would be to utilize MxToolBox’s blacklist checking tool since it will clearly display all the blacklists they check against.




So what do you do if you find out your sender domain is on a blacklist? First and foremost, you should immediately attempt to start the delisting process if the blacklist you landed on allows you to do so. Most spammer blacklists will allow you to submit a delisting request by simply submitting your IP address or domain directly to them.  Other blacklists will require you to wait a designated period of time before they automatically delist you from their database. 


You should also pause all cold outreach entirely under the affected domain if you find yourself under a blacklist.  Keep in mind, sender domains on a blacklist will suffer from lower deliverability rates than sender domains who are not present on any blacklist.  While this isn’t an ideal situation and can drastically affect your outreach campaign plans, it is always better to check so you are not potentially wasting contact email addresses.  Being on a blacklist means that you are less likely to reach the primary inbox of a recipient, thus making it much less likely that this recipient will see your outreach, which could potentially turn into a sale or convert into a new lead for your business.


On, we actually maintain an extensive resource on how to delist yourself from many of the most common blacklists that affect email marketers.  I would refer to this section of our website first before attempting to delist yourself from a blacklist.  


3. Check Your Email Copy Against Known Negative Keyword Lists

Any email message containing negative keywords will have a higher chance of being blocked outright and diverted to the spam folder by a spam filter. If you are noticing a spike in spam rates half-way through an email campaign, it could be due to the use of negative keywords, so it is worth the time to examine your email copy before continuing any campaign.


A negative keyword in relation to email is essentially any and all keywords that are known to be associated with the language commonly used by spammers. Typically, negative keywords are associated with language attempting to get recipients to immediately act on an email, whether it’s language trying to persuade users into signing up for something with the promise of “Money back guaranteed” or “Credit Cards Accepted”, or trying to get them to click through a link with some sort of promise associated with it. Thankfully, most of these negative keywords are known and there are various lists online that keep track of the bad keywords for reference.  When writing an email copy, you should always refer to a negative keyword masterlist such as the one on Warmup Inbox’s site.  This can save you the headache of having to rewrite an email copy in the future if you accidentally include a negative keyword.

It can be extremely easy as an email marketer to accidentally write an email copy containing negative keywords, especially if you are working within an industry that spammers will typically mimic or spoof with their email content. The best way to check if your email content utilizes negative keywords is to simply run a test email through one of the various negative keyword checking tools across the internet, such as

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4. Re-verify Your Contact List

Earlier, I touched on how it is possible for your own sender domain to suffer deliverability issues due to broken DNS records. Much in the same way your own domain can break, this can also happen to the domains associated with the email addresses under your contact list for outreach. Even when you perform your due diligence when cleaning an email list, a domain can break seemingly at a moment's notice. 


When you have a list of thousands of email addresses, all under their own domains and workspaces, there is a high likelihood that a handful of these email addresses will break and/or no longer be able to accept mail between the time you verify your contact list and actually contact them. This is especially true for drip campaigns, or contacts gathered via a lead funnel, where email addresses are gathered over a long duration of time and fed into an outreach campaign. For this reason, we strongly urge people to run their contacts through email verification services such as EmailListVerify on a normal basis to ensure you are only utilizing clean emails.

At, we go to extreme lengths to verify all contacts within our warming network, multiple times a day, for this exact reason.  It’s not uncommon for an email address to be perfectly healthy and normal at one moment, and then become broken and unable to receive mail moments later. If you are having spam issues within your email campaign, it never hurts to re-verify and reprocess your contact list just to make sure that all bad or problematic emails are identified and removed from being contacted, or any further contact.

5. Make Sure That Recipients Can Easily Unsubscribe From Your Emails

Unless you are manually sending out each and every outreach email to your own contact list, you need to make sure that you are giving recipients options to stop receiving emails from your sender domain. While this is just good practice in general and showing your recipients respect, it is also legally required by law in many countries. Specifically for the United States, this is 100% a requirement via the CAN-SPAM Act and this still applies even if you are from a country outside of the United States sending emails to those living within USA borders. You ABSOLUTELY need to include unsubscribe links in all your outreach emails, no matter what the subject or purpose of these emails are.


All reputable email sending services should give you the resources to include these unsubscribe links within your email copy. You can place these in the body of your email message or even the signature of a sender email address, but no matter what you should be including these links in every single email you send out for a cold outreach campaign.













In terms of deliverability, not including these unsubscribe links or including information signaling that an unsubscribe link is present within the body of an email address can be enough reason for most major ESP providers to flat out deny your outreach if they have an indication that an email is being sent out from an automated tool to a previously uncontacted email address. 


Including the unsubscribe link within all emails you send out have a tendency to reduce spam complaints overall towards sender domains. In most of the major ESP providers (Primarily Google and Microsoft, but others also include this feature), if a user attempts to report an email for spam, they will be given the option to simply unsubscribe instead of reporting.  While recipients can still easily report an email as spam, including unsubscribe links will at least give them an option to not report you for spam and instead just stop receiving your emails altogether. In the long term, this can help maintain the deliverability health of a sender domain.

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For all email marketers, avoiding the spam folder should be one of the top priorities of any email campaign.  The spam folder and spam filters play an extremely important and useful role for the internet and email.  Email marketers can have difficulties at times when attempting to narrow down the exact reason why the outreach fell by the wayside.  As long as you are taking the time to properly setup your sender domains, setup your sender emails, as well as take the time to make sure that your contact list is clean and reliable, then you should be able to avoid the spam folder and have a successful email marketing campaign. 

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