re :I can send copies of these error messages but NOT images,

Do you mean you tried to upload an image to this forum question ?

You can only upload any .jpg or .jpeg or .png image file using the 'browse' button. You cannot upload any documents like pdf etc - you must have an image file otherwise you would not have been able to put it in a pdf.

Gmail auto saves all sent mail in the server default 'Sent Mail' folder so if using imap then you should auto see them in the default imap Sent Mail folder regardless.

re: Saving copies of sent mail In Account Settings > Copies & Folders for gmail account Usually, for IMAP account- you do not need to select 'Place a copy in' because gmail does it automatically. So as a rule that option should not be selected.

If you want a copy in Local Folders account:

• Select 'Place a copy in'
• Select 'Other' and choose 'Sent on Local Folders'

The info I have managed to locate says: Gmail regards bcc to yourself as a duplicate and ignores it as you would have copy in the Sent Mail folder. Here's a thought - You could try to outwit gmail by putting yourself in the gmail contact list to see if it then works for bcc to self. I would be interested to know if that works.

re :I don't think reinstalling Thunderbird will help, Correct.

Can I assume you have got all of your gmail accounts set up to use 'Authentication Method: Oauth2' for both incoming server settings and outgoing smtp?

This is a reply to my "plea for help". Late yesterday, Thunderbird did maintenance on my folders and this morning, I received mail like there was never a problem! Folder maintenance hasn't been done before. Now Thunderbird has added an automatic maintenance which should eliminate most future problems.