Impossible d'envoyer ou de recevoir des e-mail

[peer]

Thank you @rodinux and @jarod5001 for your help.
It is finally solved.

Mail loops back to myself - probably related to 12.1 upgrade

Thank YunoGod it is finally fixed, I was pulling my hair out. It was just a couple of easy things (I do not see any relationship between them) but, as they were happening at the same time, it looked very confusing. I noticed the contents of my /etc/postfix/virtual-mailbox-domains file did not include my subdomain, only the domain. I just included the subdomain by enabling email for that subdomain on the domains section of the webadmin interface. That fixed the mail-loop-back-to-myself problem. …