I have an exchange 5.5 server running.I can receive emails
through my exchange but when a client tries to send any mail
using smtp it gets sent back to the sender. Internal email
is handled with no problem just any mail ouside of the LAN
is where i cannot figure this out. I have IMS installed but
am not sure how to set it up. My mail and smpt server is the
same. Do i have to run DNS on my server and create a MX and A
record?

If anyone has any examples use
mydomain.com as an example to give me an idea..Thanks