Thanks for the update. If my provider ever blocked my business from running an SMTP server on port 25 I would immediately switch providers and then call or write my previous provider a letter explaining why they were no longer getting my business. However, that having been said... I've seen ISP's block certain ports for residential accounts to try and keep people from running servers, but usually just changing the port to a non-standard port for the particular type of server is good enough to get around it (I'm not advocating breaking any explicit rules here). Also, sometimes SMTP servers that are running open relays will find their IP Address listed on a blacklist, which can certainly cause problems.

>Provider was blocking SMTP mail not using their mail server!
>
>Lots of providers are doing this, catching spammers is objective.
>
>Thanks.