Forgot to say , all other email addresses that are set up are working fine.

I have what seems to be a similar issue.

Since the automatic installation of Thunderbird 78.4 today I am not receiving any incoming Email via IMAP with my three indepedent Gmail accounts. One a generic Gmail and the other two with Email hosted at Google Apps.

I've attempted to see what happens in Safe Mode. Nothing.

It seems Gmail and Thunderbird are no longer talking since the upgrade.

Since Thunderbird's latest update, one of my email accounts is no longer receiving emails. I have removed the account and tried to re-add it, the image shows what Fasthost need for the email account, the black box is the 'Set up' window from Thunderbird. I have logged into the email account via Firefox, so the password used in the set up window is correct, not showing for obvious reason, I can also see new emails. Any suggestions please? If you need more info let me know. Thanks in advance.

See this post about fasthosts and TLS:

https://support.mozilla.org/en-US/questions/1303932

See this post about fasthosts and TLS: https://support.mozilla.org/en-US/questions/1303932

This worked perfectly Thanks