Thanks for providing more information. Unfortunately, I still cannot reproduce the problem. This time I tried using a Hirsute VM instead of a container, but everything worked as expected. I was able to send an email from inside the VM, the email went through without problems, and I received it successfully.
You mentioned that you experience the issue even if you configure postfix to act as a satellite system. Could you perhaps provide the configuration files you used to do that? I did the same here, and I think it is unlikely that the problem is in some configuration file, but hey, here goes nothing... Also, and I apologize if you have already done this, but please make sure that your Hirsute system is up-to-date. I'm using a completely up- to-date Hirsute VM with absolutely nothing extra installed except postfix and sasl2-bin. Thanks. ** Changed in: postfix (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1916541 Title: smtp "fatal: unknown service: smtp/tcp", probably after libc upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/postfix/+bug/1916541/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs