spamhaus.org is blocking our IP because we send mail using multiples domain names from a single IP.
The message is
A device (computer, server, mobile phone, etc), or an app on a device that is using aaa.bbb.ccc.ddd is infected, badly misconfigured, or compromised. It is making SMTP connections with multiple unrelated HELO values on port 25.
The most recent detection was on: May 18 2022, 10:20:00 UTC (+/- 5 minutes). The observed HELO values were xxx yyy zzz ,...
We have a lot of different domains for emails (one customer = one domain), and all the emails are sent from the same IP (Multiples different server using the same internet gateway).
How should we handle this use case ? We currently use exim4 as a mailserver on the multiples servers.