Compacting removed marked as deleted emails. Have you deleted emails from the 'Sent' folder ? If no then it will not compact as there is nothing to remove.

Thank you. I appreciate your reply.

I wonder if you may have any idea about the larger issue I experience, which is set out in this question from some time ago:

https://support.mozilla.org/en-US/questions/1256398

The size of space available to be saved is now exceeds 7GB, and I have compacted every folder individually with little effect.

Any advice would be gratefully received.

re: compacting issue Are you talking about an Imap or Pop mail account ?

Suggest you enable the following so you have an idea of the size of that dratfs folder. 'Menu icon' > 'Options' > 'Layout' > select 'Folder Pane Columns' Then at top right of Folder Pane click on the small icon and select 'Total' and 'Size'. See image below as a guide.

I notice in image you have eg: Drafts 298 new drafts. Is that correct ? Draft emails are usually deleted once the drafted email has been sent.

Note the 'Size' of Draft folder. Delete all draft emails that have been sent. Then compact the 'Drafts' folder. Did the 'size' column show reduction?

Report back on results.

Thank you for your message!

Just quickly, this is a POP account.

I will look at the other points you raise and get back to you in a day or two :-)

Best wishes