First I'd download another email app (maybe em Client, it is free for 2 accounts so it is a good testing option) and test that one account with it. It is possible that that 1 account has a settings issue for external access.

If it works there, then I'd backup your profile in Thunderbird, delete it, and then create a new profile. I'd setup the problem account first to see if it works in the new profile. If it does then add your others and uninstall em Client. If not, then you can just restore your old profile.

Here is some information on Thunderbird profiles https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data

If it works in em client but not in Thunderbird (new profile) then that would tell me there may be some type of bug that is exposed only while attempting this one specific account setup. - doubtful but it doesn't mean it isn't possible.

You could keep em Client for that one account until a fix is found for why Thunderbird isn't working for that one specific account

Thanks for the reply, I have downloaded emclient and loaded my problematic email address and it does not work on both imap and smtp. I added a second bt email address and it works perfectly. I went onto the bt webpage again and checked that my accounts were active and there was not a problem. BT were adamant that there was no problem their end and that it was just a thunderbird problem but obviously not!! Any further advise would be appreciated. I would be most loath to chuck away my bt account as my primary address is fast approaching its silver anniversary :) and have been using thunderbird for donkeys!

I use BT and had an issue with Thunderbird getting mail.

Note: I could easily logon to the standard webmail via : https://home.bt.com/login/loginform

Then I discovered there were two places I needed to logon to webmail. BT help does not tell you this.

It turned out that the BT and Yahoo servers are not in synch.

So I used this link to logon: https://login.yahoo.com/

Reset the password to the same password you are currently using to access bt webmail and which is also the same as being used in Thunderbird bt mail account.

If for some reason, you are redirected to anything other than what that link says above, eg; the bt standard webmail login, then clear your browser cache and re try.

Once I had done this, the yahoo and bt servers were back in sync and everything has been good since.

Maybe it will work for your case.

Ah, okay well that is "good" we know now it is a setup issue on the server side. In eM Client click on Menu -> Tools -> Operations and then click the Errors tab. That will list the issues it is having attempting to connect to the server to access that email account.

You can take a screenshot of that window using ALT + PrtScr or you find that information in a text file in C:\Users\[your username]\AppData\Roaming\eM Client\Logs\[the date] Auth.log (see the example screenshot attached)

and send it to BT support. Hopefully, they can use that information to better diagnose the issue you're having.

Good luck!!

I have spent nearly three hours on the online help desk with BT today, nothing seemed to work and we were chasing our own tails ending up with the same problem. Eventually the girl on the other end changed my password to a very secure "welcome321" and it seemed to work...yay! After some lunch I tried again to access my email account to no avail and on the BT website it stated I had input the wrong password....:( Again on the on line help line a different person (Male) tried to help me and after half an hour he just cleared the line leaving me dead in the water (How helpful can BT be?) After much tweaking myself (bearing in mind I am 74) I think I have finally managed it, and thunderbird seems to work. Thank you all for your replies (and with my luck..see you tomorrow :) )

Bravo sir! Way to stick with it!!