Problem Forwarding Mail...Help?

Recently, the last few days, whenever I try to forward an email, I get an error screen saying that I cannot use the current server, in this case, Bellsouth.net. The forwarded message simply goes into the OUT folder. The wierd thing is that I can send and receive emails with my bellsouth.net server, its just when I FORWARD email that I have this issue. I can't be the only person to have had this happen to them.
Can anyone suggest a fix to this problem?
Thanks

 

Settings

incoming Mail Server: pop.att.yahoo.com
Outgoing Mail Server SMTP: Bellsouth.net (also tried smtp.att.yahoo.com)
Use only this server box checked
Port 995, Use SSL checked
Authentication: Password

 

Mail forwarding problem

Can ANYONE help me with this?