My server was listed twice in a 2 months time window in backscatterer.org blacklist, for a low severity. I'm not finding anything about the reason of blacklisting. Would there be anyone to help me to find the reason ?
I am on a Debian Jessie server using postfix with dovecot, protected with fail2ban on authentification attempts. I may have forgotten something on the configuration, but there were no problem in the past time, server was nearly never listed.