Using the .Mac Mail SMTP server
If your email application supports authenticated SMTP, you can use smtp.mac.com as your SMTP server. This allows you to send mail from locations where you cannot use your ISP's SMTP server.
Mac OS X Mail, Outlook Express 5.02, Eudora 5, and Netscape Communicator 4.7 support authenticated SMTP.
Mail is set up to use smtp.mac.com for .Mac Mail accounts by default.
In Outlook Express version 5.02 (which comes with Mac OS 9.1), choose Accounts from the Tools menu, double-click your .Mac Mail account, type smtp.mac.com in the "SMTP server" field, click "Click here for advanced sending options," and select both "SMTP server requires authentication" and "Use same settings as incoming mail server."
If you set up Netscape Communicator to use smtp.mac.com, Messenger prompts you for your password when you send email.
Note: Some ISPs restrict access to the TCP port (25) used by SMTP. If your ISP is blocking port 25, you can use your email application to change the port to 587 and try again. If you continue to have trouble sending mail using smtp.mac.com, switch back to your ISP's SMTP server.