I can download my email, but sending is failing?

[admin]

The two most common issues here are Authentication and port blocking. First, check to see that you have the "My server requires authentication" box checked on the Servers tab of the account properties in Outlook or Outlook Express. Other mail clients should have a similar setting. Second, many ISP's block port 25 (SMTP) and require that you use thier SMTP server for sending email. This problem can be identified by testing the following command via command line (START-->RUN-->
type "command"): telnet mail.yourdomain.com 25
A failure on this test indicates that, either you are behind a firewall that has this port blocked, or your ISP is blocking the port. In this case, you will need to contact your ISP to resolve this.