not sure how to title this question...
we run an exchange server with around 80 internal users, all outgoing mail is relayed off a smart host (ISP smtp server) so nothing is actually sent to the world via our server. i wanted to check the server, locally i can telnet to port 25 with no issues and receive the esmtp service ready reply. whenever i do it from an external address (off our local network) i receive unable to connect error 10060.
can this cause problems with SPF records, and reverse DNS ? should my exchange server be able to accept smtp requests, requiring authentication before i am able to send from external addresses? if so how...
also the exchange server is behind a NAT (asa) device, more than likely thinking that the nat is not configured to route the smtp 25 request to the exchange server..
thanks