Did the account work prior to two weeks ago, or is this a new account? It may help if you post server information, possibly a screenshot of tools>account settings>Accountname>server settings, and tools>account settings>out going server SMTP.

Thank you!

Seeing the actual error message may help. I was anticipating that the server name would include the letters kcom.com, but you have a different one. Is the email id correct for you: email@(domain name). It is unusual . Could that be the problem?

Those are the credentials that I have always had, everything was working fine until a couple weeks ago. I am really baffled.

Okay, I'm baffled. Is there more in error message than what you posted, such as a timeout? What is the actual ISP? kcom.com? My knowledge of networks is limited and I am hoping someone with more such knowledge adds their insight to this thread.

ISP is Eclipse. I have been on online chat with them for hours and tried many things, but nothing has worked. Thanks for trying to help. I think I'm going to have to re install thunderbird and start again, or begin using Outlook instead. Very frustrating as I have literally never had this problem before and have been using Thunderbird for years.

Reinstalling Thunderbird won't help UNLESS you also start with a fresh new profile, of which neither is necessary. If you still feel like trying to solve this, let us know in your next reply and we'll pick up where you left.

Thanks Stans, I am hoping to get help from a friend of mine this evening to try and solve this once and for all. I am fed up with Eclipse who are my ISP, and Global 4 network who own them and apparently have known there is a fault on our internet line for a while, but have only just sent an engineer out to solve it yesterday. I had no idea they were doing this, and every time I have been in contact with them they tell me everything is fine and working, despite my eclipse portal telling me that I am offline, and my internet constantly dropping out. They now say that the email problem which I started this thread with is a mozilla problem, as apparently mozilla has problems. I don't know who to believe, I just want internet and email!!! I will come back to you if we can't solve it this evening. Thanks for the help.

Of course, it is not in their interest to assist you with any Thunderbird problems you're facing, the same way we can't help you with any ISP problems. Let them attend to their service in your area, then when you have a solid internet connection, we can turn to Thunderbird's issue in case a solid internet connection doesn't fix it.