On Mon, 2011-08-22 at 13:07 +0100, Anne Wilson wrote: > <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) Once your email is out on the Internet is needs a genuine Internet email address. xxx.lan is known only to your internal system and it is not an Internet email address. Care to show the headers of your outgoing email ? (cover-up the bits you want to keep private) -- With best regards, Paul. England, EU.