Many companies that provide DSL and broadband INTERNET service are blocking outgoing r-mail. No, not all outgoing. Just any outgoing that is not from the account they give you. This is a punishment of the innocent for the the crimes of unknown criminals.

In effect, your local ISO is telling you that if you have more that one of two e-mail account, you must be a spammer. Actually, spammers use hundreds of accounts. The is no reason a typical user should  not have at least ten different accounts with ten different , but legitimate companies.

Here is just one of many complaints about this gowning practice.
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Port 25 Blocking ... e-mail sent via the Internet is routed through the port 25, the channel USED for communication between an e-mail client and an e-mail server. Even though port 25 blocking will probably become an industry standard...blocking allows ISPs to block SPAM sent out through their networks, but it tends to punish the innocent that have a need to send through e-mail servers other than those belonging to their ISP...
This list contains some of the major ISPs that block port 25 on their servers:
AT&T (can be unblocked at the request)
MindSpring
BellSouth
MSN
CableOne   
NetZero
Charter
People PC
Comcast ATTBI
Sprynet
Cox
Sympatico.ca
EarthLink
Verio
Flashnet
Verizon
MediaOne
...
http://www.postcastserver.com/help/Port_25_Blocking.aspx