The message is saying failed authentication. So I guess you have not changed your outgoing password in Thunderbird after changing it with your provider. https://support.mozilla.org/en-US/kb/password-manager-remember-delete-change-tb

Hi Matt, Thank you for the quick reply. I do have those saved passwords already. These are the same PW's that work when accessing thru the Comcast/XFinity website. See Attachment Wouldnt you want it that way. If changed in Thunderbird wouldnt they also have to be changed at Comcast/XFinity Website?