Here's my response from a different thread:
I have a sbcglobal.net account, here's what worked for me on the Droid Incredible:
Email Address: email@example.com
Password: your password
Server Port: 995
Security Type:Click on "SSL"
Outgoing smtp: smtp.sbcglobal.yahoo.com
Security Type: None
Server Port: 25
The last 2 fields I listed actually populated automatically and worked fine.
Here's a listing of many POP servers and their incoming server names:
Answer Center | AT&T
A list of outgoing SMTP Server Hosts:
ISP Outgoing SMTP Server Hosts - AOL, Cox, Comcast, SBC, AT&T, Adelphia, Roadrunner, Earthlink and Others - host45.com
Hope this helps.