Question: I can't send (but can receive) mail and my ISP is Earthlink.

Explanation:

In order to prevent SPAM, Earthlink has started blocking port 25 for all SMTP servers other than their own. This is the port used to contact Cornell's SMTP servers when you send mail. This will not prevent you from checking your mail, only sending.

The resolution to this problem is to set the SMTP server field in your mail client to "mail.earthlink.net".
In order to recieve mail replied to your messages, set your reply-to address to your Cornell email (e.g. "netID@cornell.edu").

For more information visit Earthlink's help site at this address: http://help.earthlink.net/port25/

Please contact us for any assistance you might need with this process.