My mail server has been blacklisted, what do I do?

As a hosting provider, we sometimes have customers who contact us because their email messages are bouncing back with a message saying that their mail server appears in some blacklist and delivery has been rejected.

Unfortunately, most email traffic around the globe today is spam, and mail providers work hard trying to filter out as much junk mail as possible at the server level to save users the work of having to go through hundreds of emails to find one that they actually care about. To do so, many providers rely on various “blacklists” maintained by 3rd parties, such as SpamHaus or SpamCop just to name a couple (there are hundreds).

You can also use a tool such as MX Toobox Blacklist Check to see where your server is listed.

Why did my server get blacklisted?

There are many reasons why a mail server might get blacklisted. Here we focus on the most likely causes for ENOISE customers.

  • Your website could have been compromised and could be sending mass mail using your hosting account without your knowledge.
  • If your site is hosted on a shared hosting plan the problem could be that another site hosted on the same server could have been compromised.
  • Sending legitimate regular newsletters or group emails can sometimes get your server temporarily blacklisted.
  • A mailbox on your hosting package could have been compromised and used to send out spam.

What do I do know?

Fortunately, most blacklists will only temporarily block a given mail server, so in many cases the problem resolves itself after 48h or so. However, you also have the option of contacting us to help you get your server delisted.

We also recommend changing your mailboxes passwords and reviewing your site’s security.

What can I do to prevent this from happening again in the future?

  • Make sure all your mailboxes use secure passwords.
  • Keep your website secure and up to date (including all plugins).
  • If you are sending out regular newsletters consider using a specialised service such as MailChimp or TinyLetter.
  • If you send automated emails from scripts on your site make sure you use SMTP with authentication and consider setting up Sender Policy Framework (SPF) records.
  • Finally, if your site is hosted on a shared hosting plan and you would like to be responsible for your own IPs reputation, you could consider upgrading to a VPS plan where you get your own IP address and don’t have to share resources with other customers.