Knowledge Center next icon The importance of knowing why to warm up your domain, how to warm up and how to determine success?
Nov 08, 2022
3 minutes read

The importance of knowing why to warm up your domain, how to warm up and how to determine success?


After reading this article you will know why it's important to warm up your domain and how to warm up your domain. Reminder: Domain is everything after the '@'. '

Why is it important?

If you add your domain to send e-mails via the Mobile Marketing Cloud it's really important to warm up your domain. You want to avoid that your emails will end up in the SPAM box of your respondents. This could be the case if you send an email to a large list of respondents at once, because the email-providers marks it as SPAM when a whole batch of emails (>3000) are suddenly mailed through a know domain using a new IP address.

Therefore it is important to split your first list of respondents in batches. So the first e-mail is send in batches with some time in between. The e-mail provider will check if the e-mail will be opened, clicked etc. If that's the case a positive sending reputation is built up with the mailbox providers and it's less likely the mailbox providers will recognize the next send out emails from this domain/IP address as SPAM.

When do you need to warm up?

If you’re using a new IP/Domain combination for sending email, you’ll need to properly warm up your IP to ensure inbox providers deliver your emails. This applies for all our customers who start sending with Email campaigns. Basically this means sending low volumes of email on your new IP/Domain combination and then slowly increasing the volume over time. This provides ISPs time to recognize, identify, and evaluate your sending practices to make sure you’re a legitimate sender.

As a general baseline, you should send at least 50,000 emails per month at least twice per month (for 100,000 emails total) in order to need to warm up your IP. (This means that if your email volume is going to be really small (<3000) but steady on a dedicated IP, you don’t need to worry about warming up—you’re off the hook!) Most reputation systems only store data for 30 days, so you should not go 30 days or more without sending on an IP. If you do, then you will need to warm it up again.

How to determine if it's a success?

1. You split your list of respondents in batches. First batch can be 1000, and from there you can double the batches.
2. Send out the email to the first 1000 respondents.
3. Check the e-mail statistics after 60 min and especially the bounce rates and the complained rates. If the bounce rate is below 5% and the complained rate below 0.25%, you can continue to send out the next batch (which is 2000). You will check this statistics as well and if the bounce rates stays below the 5% and the complained rate below 0.25% you can speed up the sending of the batches (for example from now on, 30 min, 15 min, 15 min etc). Important to check the statistics in between.

If the bounce rate is above 5% or the complained rate above 0.25% it's important to decrease your next batch (for example 500). This will decrease the bounce rate & complained rate and from there on you can build up the batches again.

Deliverability issues

What to do if I encounter deliverabilty issues during the warm-up phase (bounce rates/complained rates stays to high?)

  • Pause sending or reduce volumes to allow spam filters to adjust to the new IPs.
  • Stop sending to mailbox providers where policy blocks occur; then troubleshoot and fix the cause. Resume sending only after the issue has been fixed.
  • Check to see if you accidentally sent to:
    • An unsubscriber list
    • A large number of unengaged subscribers

If you did, hold your volumes at the current level for a few days, then start back up on the original warmup plan, and make sure to send to engaged subscribers right away.

Do you want to read more about e-mail deliverability click here.


Below you find a video on the importance of warming up your domain.

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