We have had an Exchange Server 2003 for years. We have only used it internally for Public Folder sharing. I have hesitated to use it as an external mail server primarily because CenturyLink technically does not allow mail servers on their network and I would have to use CenturyLink as a smarthost on port 25. The whole idea of CenturyLink cutting us off for any reason has stopped me.
I had another customer try Forefront Online Protection for Exchange for their SBS2011 Server and it appeard as though Microsoft actually let this customer use them as a smarthost on a port other then 25. Maybe I am mistaken.
Anyway.... are there and services available that will let me use them as a smarthose on some other port other then 25 so I can open this Exchange Server up as a full blown mail server and "get around" getting involved with CenturyLink?