May be it is related to https://bugzilla.redhat.com/show_bug.cgi?id=1441601#c8 ? Are patches from there in ubuntu?
** Bug watch added: Red Hat Bugzilla #1441601 https://bugzilla.redhat.com/show_bug.cgi?id=1441601 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1691333 Title: upgrade to 52.1.1 breaks smtp starttls on 16.04 and 17.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/1691333/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
