sending, contacts not working with stmp account

[jilld]

I upgraded from Zimbra Desktop 1.0.4 to 2.0 on Windows XP.

I have two email addresses that I use with it. One is a Yahoo account that seems to be working fine. One is a godaddy.com account that is receiving email but not sending. Every message comes back almost instantaneously "Invalid Addresses". Also, when I am composing a message from that account, the To: and Cc: buttons are disabled.

I have tried: rebooting, changing ports, and changing SSL encryption setting. I checked with godaddy, and everything seems to be fine on their end.

Any suggestions!? Thanks in advance,
Jill