Most folk with an issue have done as Google asked and turned off less secure apps. Try checking it is turned on.

https://myaccount.google.com/lesssecureapps?pli=1

Already sorted that issue two weeks ago. Has worked for the last two weeks now has died again.

Did you check, or just assume you had it sorted?

Please add the troubleshooting information to your post To find the Troubleshooting information:

• Open Help (or click on three-line-icon and select Help)
• Choose Troubleshooting Information
• Use the button Copy to clipboard to select all. Do not check box "Include account names"!
• Paste this in your post.

Of course I checked. I did notice that in Tbird passwords the mail account password had been changed so I deleted the incorrect one but Tbird never asks for the password when getting mail. Here's the troubleshooting information:

 Application Basics
   Name: Thunderbird
   Version: 60.0
   Build ID: 20180731173940
   Update Channel: release
   User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.0
   OS: Windows_NT 6.1

   Multiprocess Windows: 0/0 (Disabled)
   Web Content Processes:
   Stylo: content = true (enabled by default), chrome = true (enabled by default)
   Enterprise Policies:
   Google Key: Missing
   Mozilla Location Service Key: Missing
   Safe Mode: false

 Mail and News Accounts
   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

   account13:
     INCOMING: account13, , (imap) imap.gmail.com:993, SSL, OAuth2
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true

   account14:
     INCOMING: account14, , (imap) imap.gmail.com:993, SSL, OAuth2
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true

   account15:
     INCOMING: account15, , (imap) imap.gmail.com:993, SSL, OAuth2
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true

 Crash Reports for the Last 3 Days

 All Crash Reports

 Extensions

     Name
     Version
     Enabled
     ID

     Lightning
     6.2
     true
     {e2fda1a4-762b-4020-b5ad-a41df1933103}

 Security Software

   Type: Name

     Antivirus:
     Antispyware:
     Firewall:

 Graphics

     Features
     Compositing: Basic
     Asynchronous Pan/Zoom: none
     WebGL 1 Driver WSI Info: EGL_VENDOR: Google Inc. (adapter

passwords will always change with oAuth. it stores a "token" when you successfully authenticate with the gmail mail server that looks nothing like your original password, it looks more like a random 43 character string and the user name changes to a guid.

What anti virus do you use?

Use AVG Free and have done for years

On trying to delete and re-configure e-mail account it continually fails so attempted using other settings and received 'Programming bug' error.

Should have included this in previous post. Attempt to create new account. The user name and password works fine when signing into Google webmail.

It seems AVG has taken it upon itself to block my email account (Email Shield) but there seems to be no way to 'tailor' the way it works so have just turned it off and presto receiving and sending emails again. I am now going to highlight this to AVG. Thank you for your time and patience on this problem.

I suggest you move on from AVG, I have.

One thing to seriously consider is that Microsoft do not scan mail with Defender. Why is that? I think it is because it is unnecessary.

Thunderbird does not execute scripts in the body of email, so unlike other mail clients you can not get "infected" by opening a mail.

Thunderbird does not load remote images unless told to, so you can not get a drive by infection from loading an image (although I have never heard of it happening)

The only real risk vector is attachments and as they are saved to the temp folder on your computer before they are opened any virus scanner worth disk space will scan the file as soon as it is written and prevent it loading if it has issues.