Sending of message failed.
The message could not be sent because connecting to SMTP server 88.198.**.** failed. The server may be unavailable or is refusing SMTP connections. Please verify that your SMTP server settings are correct and try again, or contact the server administrator.
Some people are able to connect, others are not. I just spent 2 hours remote controlling someone's computer to try to get it working for them. I deleted the account on the server and reinstalled it, installed Thunderbird 3 on their computer and duplicated my Thunderbird 3 settings as well as trying all possible combinations and even trying to use my login to send mail--no go.
Using port 587. I finally had to set them up to use smtp.gmail.com to send mail, also with port 587, so their isp is not blocking port 587.
They are able to receive mail from the server without a problem.
I am not able to send mail using Thunderbird 2 on either port 25, port 2525 or port 587, but Thunderbird 3 is able to send mail from my computer using port 587.