outlook unable to send test message on existing email account

I have had 2 email accounts setup in my Outlook 2003.
hotmail (default) and my comcast.net email account
I copied all the settings from my outlook express account where they worked
fine, they worked fine in Outlook 2003 also until 4 days ago, thats when I
noticed mail from the comcast account stopped downloading.
I checked the settings today, and when I press the 'Test Account Settings'
button I get an error message which says 'Unable to send test message, Please
verify email address field'.
The email address field is good (unchanged) and outlook Express still down
loads mail fine from the address.

Appreciate any help.