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Why do I see some valid email addresses bouncing?
Why do I see some valid email addresses bouncing?

Learn why emails are marked as bounced and how you can prevent it.

Mike Pauer avatar
Written by Mike Pauer
Updated over a week ago

Bounces are determined by the receiving server, and it means the server rejected your email. It can reject for any number of reasons, and it doesn't necessarily mean the email is bad.ย 

It can also be confusing as a 1:1 email from a sales person might go through, but a marketing email does not. This is because the receiving server knows if this is a direct email or an email sent to an email list (mass marketing email). Some things that could cause a server to bounce include:

  • Invalid address

  • Closed inbox

  • Limits on size of attachments

  • Limits on size of images

  • The wording in the email

  • Strict fire walls blocking unknown IP addresses

  • Strict rules regarding emails sent via SMTP relay

For the best deliverability

  • Avoid "spammy" words of phrases; our Email Tests in the email builder can help identify those

  • Limit the size of your email to 10MB at the max (some servers will be stricter than this)

  • Limit the use of images to 1-2 images; some very strict spam filters will trigger if there are more

  • Avoid sending mass marketing emails too frequently (more than once per week)

The best way to guarantee deliverability is to have your recipients whitelist our IP range. We realize you won't always be able to do this, but it will make sure your marketing emails get through. Here is our range:

  • IP Ranges: to to to to

  • Prefixes: and

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