I have two PCs, both with all emails working perfectly, then suddenly I could send talktalk emails from one but not the other. My personal email address linked to my website hosted elsewhere worked perfectly on both. Then, later in the day, I found that I could send messages from all but one talktalk email address on one of the PCs. All were set up absolutely identically.
I deleted the rogue account on my PC and set it up again. Still no joy. In the end, I became so fed up that I exported the Thunderbird settings from the PC where they all worked to the other one. I was forced to enter my password again, but after that it worked.
For anybody else forced to do the same thing, remember to take into account anything you have saved in local folders. No big deal luckily, but I realised that by transferring the settings I had lost all the council tax receipts I saved on one PC but not the other. Possibly other things as well, but nothing I can't live without.
I forgot to mention that after deleting the troublesome account, I first tried setting it up again by letting Thunderbird find all the settings automatically. It said it had been successful and it was populated with my emails, but I still couldn't send from it. Then I noticed it had inserted the wrong port number. Manually correcting it still wasn't successful, which is why I had to take the more drastic action of transferring all the settings from my other PC.
