SBC blocks port 25 (SMTP) for outgoing mail

Problem: You can't reach a non-SBC mailserver via your SBC DSL connection.

Solution:
There are several workarounds/solution:

• Use an alternate SMTP port with authenticated SMTP such as port port 587. Check with mail provider.
• Use the SBC mailserver with authenticated SMTP (see this link). This works for any email address, not just sbcglobal.com.
• Request to opt-out of port 25 blocking:
  

  "To request removal of the filter, use the Abuse of Service form at http://help.sbcglobal.net/servabuse.php to contact our Abuse team and choose the "Opt-Out Port 25" under Abuse Type."

Further reading:
Why am I unable to send email via other university, company or mail hosting provider mail servers (Port 25 block)