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Why Am I on an Email Blacklist?

Tags: Email,  Security 


This guide is intended for Hostwinds clients whose service is older than 30 days and have found that their IP has been blacklisted.


If you find yourself on an email blacklist, there could be several reasons:

  1. The previous owner of your service's IP you're using had been blacklisted for sending an email.
  2. Legitimate emails you sent were reported as spam by a recipient.
  3. Someone in your organization is knowingly sending mail considered spam by the recipients.
  4. Someone in your organization is unknowingly sending mail considered spam, whether by local computer infection or stolen credentials.
  5. Someone has broken into your hosting/server and created accounts to send spam.
  6. Someone has set up malware on your hosting/server to do the same.
  7. Someone is sending spam pretending to be from your domain.
  8. Someone is sending an email through your server's email server.


In the case of 1, a removal request should be all that's needed.

For 2 and 3, an adjustment of the types of mail being sent may be necessary, or any mailing lists of users edited.

The possibility of 4 is easy to track down (mail server logs will show all mail from one account) but may be harder to fix.

5 and 6 should be fixable by changing email account passwords and/or doing malware scans on the hosting / server.

7 should be fixable with proper DMARC/DKIM/SPF records set up in DNS and on the mail server.

8 is specific to VPS and dedicated servers and is what's called an "Open Relay" -- configurations should be adjusted to prevent outside users from sending mail, including SMTP password verification.

These are only a few possible reasons to have your hosting/server IP on an email blacklist, but we'll be happy to help you figure out why you're having issues sending mail.

Please join us in LiveChat or by filing a ticket with the required details to the technicians to investigate, and we will let you know what we find and what can be done to fix it.

Written by Hostwinds Team  /  June 5, 2021