Cannot delete email from mozilla
 

My harddrive spontaneously ran out of space today, so I went to look for what was hogging all of the space. The mozilla mail folder takes up nearly 900mb. I've been deleting mail somewhat regularly, so I go back into mozilla and delete a lot more, check the mail file again, and its still the same size. Somehow my mail is not being deleted. How can I fix this?

After deleting emails you must compact the thrash folder because mozilla continue to keep the deleted messages eventhough you don't see them. Also compact all your folders to reduce space.
To do this right-click on each folder and choose compact this folder.

Regards