Mail On Os X 10.2, It won't authenticate Options

[c_r0c]

I have been trying to set up my default mail server for the mail option in Mac OS X 10.2. It won't authenticate? I have put in the information as incoming.verizon.net, and the same for outgoing. When i click on a link to send an email from some webpages, my mail opens up, sets up the email, then tells me that I cannot send the email because my email address is not authenticated. Any suggestions?

thanks, MC