> <anne at xxxx.org>: host mailhost.zen.co.uk[212.23.3.98] said: 550-Verification > failed for <anne at xxx.lan> 550-Unrouteable address 550 Envelope Sender: > Domain must resolve in DNS! (in reply to RCPT TO command) It looks like your outgoing mail from your local user(s) needs to be masqueraded or the whole server does.