Help with outgoing Outlook XP.

[yahoopopsuser]

Whenever I try to send a message with Outlook XP from my Yahoo Account I get this message:

Error:
Task 'localhost'-Sending and Recieving reported error (0x80042109)
Outlook is unable to connect to your outgoing(STMP) e-mail server, and to contact my ISP if it continues.

Could anyone help me. I'm using YahooPops 0.6. Any help would be appereciated!