All staff using our internal network have email addresses at a specific domain, say @specificdomain.com. Incoming messages are not delivered directly to the internal Exchange server, however - instead they are downloaded using a POP Connector from a central mailbox on the @specificdomain.com, provided by a third party. I've recently added a new email address on our third party hosting package, but this is not used by one of our Exchange users and is intended for them to download messages directly using POP3 to their individual computer. This is working fine, except when internal staff try to send messages to this address, they get an error message back saying the user isn't known on the domain. Obviously this is because they don't have an account on our internal Exchange server. Is there a way I can get around this? (E.g. can I tell Exchange to treat unknown addresses as external addresses, just like it would if they weren't on our domain?) Thanks in advance, Gary

Further to the above and having tested this some more, the problem distills into this: If an email address is not listed in Active Directory, then it should be treated as external and sent via SMTP. This currently isn't happening. Can anyone tell me why and how I can fix it? Thanks, Gary

Hi, You need to share the SMTP domain name or even better host your own smtp mails. http://support.microsoft.com/default.aspx?kbid=321721 Leif

Thanks, Leif. The website you linked to was very helpful and, in fact, all I had to do was tick the option on the SMTP connector to forward messages with unresolvable addresses to an external host. The problem is now sorted. Gary