As I'd been having other problems (now resolved) I tried to run the update script with a fresh download of 18.104.22.168. Unfortunately Mailman is now misbehaving.
Initially Mailman threw up the following in mail.warn:
May 13 22:44:04 ***** postfix/cleanup: warning: database /var/
lib/mailman/data/virtual-mailman.db is older than source file /var/l
I've fixed this with postmap /var/lib/mailman/data/virtual-aliases
Now I receive an error when trying to post to a list that shows in mail.log as:
May 13 23:12:58 ***** postfix/smtpd: NOQUEUE: reject: RCPT fr
om **.myisp.tld[**.**.**.**]: 550 5.1.1 <firstname.lastname@example.org>: Recipient address rejected: User
unknown in virtual mailbox table; from=<email@example.com> to=<firstname.lastname@example.org> proto=ESMTP helo=<[10.0.1.16]>
Searching on the forums I saw the 22.214.171.124 issue but my /etc/mailman/virtual_to_transport is correct.