Email Warmup Best Practices (The Complete Guide)

The purpose of the email warmup is to build up a good reputation for your email account and therefore improve its deliverability rate.

What is an email warmup?


Email warmup is a process of preparing a new (or long-inactive) email account for future email outreach, campaigns, etc.


It involves preparing and gradually sending a small number of emails from a new (or long-inactive) account that will improve (warmup) the reputation of your inbox so your future emails will not be marked as spam by email service providers (ESP).


Email warmup takes about 8 to 12 weeks for maximizing the email deliverability and is recommended to keep it up running even after reaching the maximum deliverability rate.


Why is email warmup important?


People use email accounts for various reasons - either for personal use, promotional purposes - but sometimes even as a way to send out malicious or spammy content that can harm the email recipients.


Due to this fact, ESP (Email Service Provider) and ISP (Internet Service Provider) are constantly trying to determine which email accounts can be considered reliable and deliver their emails into recipient's inboxes and which can't so they can ignore their emails and mark them as spam.


The sender's history serves as a point of reference for the ESP and ISP providers that indicates how trustworthy their emails are, what type of user owns the domain/inbox, and whether or not their emails should be delivered to the recipient’s inbox.


In order to start a cold email campaign that would deliver your emails to recipients, you have to build up a good reputation for your domain, mail server, and sender email addresses first, with positive sender history that would show to ESP’s that your emails can be considered trustworthy.


The warmup process for a domain gradually improves your reputation and history - by sending out emails that recipients want to read, engage with or mark as important, you are showing that your account is controlled by a real human being and is not used for misleading or scamming purposes.


Once your email account is warmed-up, you can start your cold email campaigns that will have a higher deliverability rate and therefore higher chance that users will read your emails.


How to warmup your email account? (best practices)


The process of building up email reputation and warming up your account is pretty straightforward - you have to send out emails that would create Consistent Positive Email Engagement (CPEE).


The reason why CPEE is so important for you (and for ESP’s) is that spammers or scammers virtually never try to establish a relationship with recipients - the only thing they want is to get their emails to as many people as possible for malicious purposes.


CPEE involves many activities that recipients make naturally when receiving emails such as:

  • Opening up and reading emails

  • Replying to your emails

  • Adding people to the email threads

  • Marking your emails as important

  • Or even going to the spam folder and marking the emails as a “not spam”

These kinds of activities create CPEE and serve as signals that ESP providers pay attention to when determining the trustworthiness of an email account.


Although Consistent Positive Email Engagement is mostly dependent on the recipients and their behavior, there are a few actionable steps that you can do yourself to improve your reputation and actually warmup your email account for future cold email campaigns.


1. Use a custom domain


Custom domain is a sign for the recipients as well as for the ESP that your email is authentic and from the relevant source.


Generally speaking, custom domains are considered more trustworthy as opposed to generic email accounts that are used by spammers or scammers for malicious emails.


2. Authenticate your email account


Email authentification is recommended for every new email account - it indicates that your emails are trustworthy and should not end up in the spam folders.


Email authentification is composed of 3 important methods:

  • SPF (Sender Policy Framework) - is a record in your DNS (Domain Name System) that authorizes only chosen servers to send your emails with your domain name. SPF therefore clearly tells the ESP of the recipient, that the emails from your domain are controlled by you and nobody else.

  • DKIM (Domain Keys Identified Mail) - is a digital signature for your domain that secures your emails from altering or manipulation when traveling from your account to the recipient's inbox.

  • DMARC (Domain-based Message Authentication, Reporting & Conformance) - is a security record that requires both SPF and DKIM authentification from your domain before it allows you to send your emails. DMARC helps to prevent abuse of your domain by somebody else from outside.

These 3 types of authentification mentioned above can significantly improve the reliability and trustworthiness of your email account.


3. Personalize your emails


Creating emails that are designed for every recipient individually may increase engagement and therefore warmup your account much quicker.

Generally speaking, people respond to emails that are created just for them more positively - since they look less spammy and more genuine and “human”.


This can be applied to ESP as well - if you don't spam the same email to every person, ESP may perceive your account as more trustworthy and reliable.


4. Avoid spammy words


Spam filters are sensitive to the content that your emails contain, especially for risky words that just attract attention and mislead the readers.


Due to this fact, try to avoid words like “FREE”, 75% OFF, BUY RIGHT NOW, etc., since it will just increase the chance that your emails will end up in spam folders.


The same can be applied to click-bait titles or claims in your emails that are promising some prize but in reality leading to something completely different.


Here is a list of spammy words that you should not include in your emails (collected by Maijet):


list of spam words

5. Send your emails gradually


Sending many emails at once can hurt your reputation in the eyes of ESP’s - since it may look like you are a robot and not a real human being who is sending the emails.


Email service providers use various algorithms that check how many or when the emails were sent and received.


If you send too many emails at once, ESP’s may assume that all those emails are spammy and should end up in the spam folder or even completely block your email account.


Instead of sending a large number of emails at once, try to send your emails gradually, with sufficient time gaps between each other.


Sending emails continually will look more natural and won't affect the reputation of your email account.


6. Maintain regular conversations


Creating positive engagement and getting responses is a huge plus for your email reputation - but that is just half of the work.


When getting answers to your emails, try to keep up the conversations flowing and reply to users who wrote you back.


Having regular conversations is a strong signal for email service providers that your email account is trustworthy - which leads to a quicker warmup of your domain.


7. Add unsubscribe button


Having an unsubscribe button or link in your emails may prevent readers from marking your content as spam.


Unsubscribe links are especially important for new email accounts - if your domain is just warming-up, any spam report may drastically hurt your reputation and slow down your warmup period.


By providing an Unsubscribe button/link in your email, you are offering an alternative for the readers - instead of reporting your emails as spam, they can simply just unsubscribe.


Unsubscribe links also will make it more difficult for recipients to report your emails as spam, as a majority of ESP’s will first urge you to unsubscribe before allowing you to submit a spam complaint.


Therefore once unsubscribed, the readers won't be bothered by your emails again and your email reputation won't get hurt - a win-win situation.

unsubscribe link in email

8. Use Warmup Inbox


Warming up a new email account is quite simple but very time-consuming: you have to prepare engaging content, keep up with conversations, and continuously send more and more emails over a long period of time.


That is why it is always a good idea to use tools that are capable of automating the process of inbox warming for you, such as our Warmup Inbox tool.


Warmup Inbox is a pretty easy and straightforward tool - it sends out emails on your behalf, gets responses, creates engagement in email threads, etc. within our platform.


It contains hundreds of other email accounts that automatically communicate with each other:

Warmup Inbox automate messages

Once your email account is synched with Warmup Inbox, there are a number of ways that our tool can help automate the process of building up sender reputation:

  • Send and receive automatic emails - Warmup Inbox is capable of creating dynamic content that is sent and received within our platform

  • Pull out your emails from the spam folder - if some of your emails end up marked as spam by an ESP, Warmup Inbox will automatically pull those emails out from the spam folder and correct them as important messages (which will automatically improve the reputation of your email account)

  • Monitor email blacklists - Warmup Inbox monitors all major email blacklists and constantly checks if any of the synched email accounts are not listed in some of them.

  • Track your “health” score - Warmup Inbox tool will give you a clear overview of the sender health of your sender domain - it scores your account on a scale of 0 - 10 based on many factors that influence the email deliverability (e.g.blacklists, security protocols, the quality of your email message, etc.)


How long should you warm up your email account?


Generally speaking, it is recommended to warm up your email account for 45 - 90 days before starting your cold email campaigns.


The reason why it can take up to 3 months is that you need to create a pattern of long term consistent positive email engagement (CPEE) that can be properly evaluated by email service providers - and therefore determine whether or not your account is trustworthy.


However, keeping your email account warmed up is a constant process that should not end up even after the 90-days period.


This is because the reputation of an account changes over time, based upon a number of factors that are constantly checked and evaluated by ESP.


For example, if you leave a warmed-up account inactive for a long period of time without any engagement or positive reputation built up it will gradually become less effective at outreach and ESP’s will at some point re-evaluate your account as a new unknown domain without any recent activity history.


Therefore, it is recommended to constantly keep your email warmed up even if you don't plan to utilize it in the near future - either by continuously sending engaging emails or by using tools like Warmup Inbox to keep your account constantly active.





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