Hi Mark, My guess is that you have a `search .` line in your /etc/resolv.conf. The postfix postinst script tries to guess the machines FQDN in several ways, and one way is concatenating with a '.' the local hostname and the resolv.conf "search" domain. You can see this logic here:
https://git.launchpad.net/ubuntu/+source/postfix/tree/debian/postfix.postinst?h=applied/ubuntu/hirsute#n40 If this is the case, then this bug report is a duplicate of LP: #1906970. The reporter of LP: #1906970 claims that `search .` is valid syntax, but I failed to find a reference for this claim, with a definition of what `search .` would mean. My suggestion here is to amend your /etc/resolv.conf, you should be able to safely drop the `search .` line, then please mark this bug as a duplicate of LP: #1906970. If you don't agree with my analysis here please comment back and we'll look at this again. 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/1931801 Title: Apt install postfix fails with bad demiliter To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/postfix/+bug/1931801/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs