I've been using Thunderbird for years now but made some minor tweaks as I'm setting up an imap proxy for remote access to my debian/dovecot/postfix server.
The issue is I changed the account settings in thunderbird to use STARTTLS and port 993. It now doesn't work. I see a connection in wireshark, but then nothing happens and dovecot logs no attempt to authenticate and it just times out. I also installed claws email (which I'm using for this email) It has the same settings and works flawlessly from the same client machine I use for thunderbird. I conclude there are no routing issues or firewall issues. So the question is what do I need to do to thunderbird to get it to work with dovecot TLS / 993 ? Thunderbird: 78.14.0(64 bit) dovecot --version 2.3.13 (89f716dc2) cat /etc/os-release PRETTY_NAME="Debian GNU/Linux 11 (bullseye)" NAME="Debian GNU/Linux" VERSION_ID="11" VERSION="11 (bullseye)" VERSION_CODENAME=bullseye ID=debian HOME_URL="https://www.debian.org/" SUPPORT_URL="https://www.debian.org/support" BUG_REPORT_URL="https://bugs.debian.org/" The only other perhaps relevant thing is I did a distro upgrade from 10 to 11 yesterday. Thanks in advance Jeremy P.S. claws is very snappy!