"5.1.0 Authentication required" error message when using Eudora 5.2 and Comcast

I was getting an error message that said "550 5.1.0 Authentication required" when sending Email from Eudora 5.2 over my comcast SMTP Email server.

I spoke to a very nice Comcast technician who said that Comcast doesn't support Eudora but he was willing to try and help me anyway.

In Eudora, we went to Tools and then to Options;

Here are the settings we ended up with that made it work;

Under "Sending Mail";
SMTP Server: smtp.comcast.net
Allow authenciation is checked
Immediate send is checked
Secure Sockets When Sending: Never

Under "Ports";
SMTP Port (25): 25
IMAP Port (143): 143