Overnight my sent emails over eight years have duplicated themselves up to five times over and now the sent box is so full it wont hold emails. The message when I try to send is: "The folder Sent is full, and can't hold any more messages. To make room for more messages, delete any old or unwanted mail and compact the folder." My email provider is Eftel (nothing to do with gmail). It starts in 2014 with maybe one or two emails being copies then around 2012 it becomes three or four or five copies of the same email right up to when I commenced in 2008. Have tried compacting but this didnt make a difference. Any light shed would be very appreciated! Thank you Mozilla universe