First, I encourage you to contact the organization, as they are the Godaddy customer and should be able to answer your question. My inference is they gave you the email id and the password, which obviously are wrong or reflect an incorrect configuration. Godaddy is, to my knowledge, switching people to office365 and references to secureserver may be out-of-date. For what it's worth, you never posted a screenshot of your smtp server settings that caused the problem. And please, if possible, please rotate them vertically. :)

David: You are correct -- office365.com IS the correct SMTP server -- the stuff on the GoDaddy site referencing setups to secureserver.net must be outdated. When I go directly to the GoDaddy portal for that email address, it is the Office365 site, just as Thunderbird identified during the initial search. I tried both POP and IMAP setups, with the same result on attempting to send. Here's a screenshot of what's available regarding server settings. I hope it comes through right-side-up (it looks right here) -- I don't know why they rolled over when I inserted them. BTW: I also tried forcing it to SSL/TLS Port 465 -- same results.

I continue to think the main problem is that you, personally, aren't the customer. It may be that your password is incorrect and that is the organization's responsibility to you. Also theirs to contact Godaddy to find out why you are not connecting. Godaddy has an 800 number and prides themselves on customer support.

Good thoughts! I'm confident it's not password-related -- we just reset it using a link in an email direct from GoDaddy. I'll try (to find) the 800 number. Thanks!