From this talktalk.net article, it looks like Thunderbird's automatic setup doesn't catch the proper incoming email server information.

You should be using mail.talktalk.net as incoming server, not imap.talktalk.net.

Thunderbird will automatically try to look up the email settings. Click the Manual config button on the bottom left of the window, as you need to enter these details yourself. Enter the following details:

• Incoming: Select IMAP from the drop down list.
• Incoming Server Hostname: mail.talktalk.net
• Port: 993
• SSL: Yes
• Authentication: Normal password
• Outgoing Server hostname: smtp.talktalk.net
• Port: 587
• SSL: StartTLS
• Authentication: Normal password

Where do I find this Manual Config. Button "Click the Manual config button on the bottom left of the window, as you need to enter these details yourself. "

I have this exact same issue.

Tried the suggested settings on talktalk's FAQ page.

Didn't work.

I called up Talktalk and spoke to a Technical Manager regarding this. They said, "The reason you are unable to receive or send emails is due to a compatability issue." the only way to solve is to "Downgrade to version 17 of Thunderbiird" what a joke!

You didn't answer the question "Where do I find thos Manual Config button?". So, where?

I am sorry, the information I linked to assumes you're using the first time install wizard.

Your account is already configured, just not with the right information.

You're using Thunderbird for WIndows, so you need to go to Tools > Account settings and change your incoming mail server information to mail.talktalk.net.

This page has more information on manual configuration of your account.

Thanks very much, but I'm afraid it hasn't helped. I notice that you specify Port 993 on the incoming server, but, when I tried to change that from 143, the page vanished, and, when I re-opened it, it had gone back to 143. It does say "Default 143".