http://www.perlmonks.org?node_id=232842


in reply to SMTP and Exchange

While this isn't much of a perl question (google your non perl stuff), I'd suggest checking out this page which will explain how the relaying in Exchange is supposed to work.

It sounds to me like it may be that your box that is trying to send out is not listed in the list of hosts to relay for or your server requires authentication to relay.

-phill