Yes, it's possible. The two functions are served by two separate
daemons. For outgoing SMTP mail, you would use an SMTP server
such as sendmail and for retrieving email to a client, you would need
a POP server such as popd. There is no issue with transfering mail
between then. When an email arrives at the SMTP server and if it
happens to be the destination SMTP server, the message would be
delivered by the SMTP server (deposited in a file usually). It's left
there until an email retrieval client gets to it, this could be Unix mail
clients such as mail or it would be a POP client.
> Is it possible to run both smtp and pop3 servers on the same machine?
> If so, are they able to transfer mail from the one to the other?
> We seem to have some problem to implement it.
> Feel free to comment.