SMTP protocol not working properly

[Yescenia]

I've been using Note Pro with no problems on the last few months , much of the carriers that I'm working with are using SMTP protocol. I don't know why but suddenly that protocol is not working properly and when I do the test the SMTP is failing. Am I doing something wrong? What can I do ?
Just checking, Does Cingular Wireless has a new SMTP address ?

[Tech Support]

When the Internet Connection Wizard fails the "SMTP" test, it is usually due to a local firewall or Internet Service Provider (ISP) blocking TCP/IP port 25, the standard SMTP port.

If you have a local firewall product (either hardware or software), check the manufacturer's documentation on opening/closing specific ports.

If you are not running a firewall, you may need to contact your ISP to verify if port 25 blocking is occurring with their service.