Gareth Otte [exim-users] <28/05/01 11:50 +0200>: > I'm not sure if this is an Exim related question. Can anyone assist with
> this error message:
> I can mail this person using a different mail server program, but when
> mailed through Exim, it returns this message.
Can you resolve that domain using (say) nslookup and dig, and can you ping
it's MX?