One of the email accounts on my Debian server has been compromised (too weak password set by a client) and it was sending countless spam messages over three days.

Once I've found out that out (, I've changed the password and the spam is not being sent.

The server IP is not listed on any spamlist.

However, I get many bounces from @gmail.com addresses, with the following message:

Our system has detected 550-5.7.1 that this message is likely suspicious due to the very
low reputation 550-5.7.1 of the sending IP address. To best protect our
users from spam, the 550-5.7.1 message has been blocked. Please visit 550
5.7.1 https://support.google.com/mail/answer/188131 for more information.

The DNS for this domain is configured with SPF and DKIM (no DMARC, but previously with the same setup all was working ok).

How do I deal with this problem now?
How to tell Google that we're not sending spam anymore?


There are a bunch of good tools on https://mxtoolbox.com/ for checking blacklists.

Here's an article on how to get off of Gmail's list: https://www.rackaid.com/blog/gmail-blacklist-removal/

I used to have to contact each blacklist provider and beg :)

Good luck.

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