I have a similar issue, cannot send email from my school email address. did the steps/settings but i get this:
Sending reported error (0x800CCC67): The server responded: 421 cannot connect to SMTP server 142.204.1.21 (142.204.1.21:25)
and:
sending reported error (0x80042109): outlook cannot connect to your outgoing (STMP) email server. if you continue to recieve this message, contact your server administrator or internet service provider
and:
sending reported error (0x8004210B): teh operation timed out waiting for a response from the sending (STMP) email server. if you continue to recieve this message, contact your server administrator or internet service provider
this is on the latest version of avast home program and virus db as of May 13, 2010 21:12 EDT. I'm running Windows 7 ultimate, Outlook Professional Plus 2010 BETA version: 14.0.4536.1000 (32-bit)