My server charter.net upgraded and I had to change the pop3 server to IMAP. After doing so thousands of past emails downloaded from charter.  I could not stop it.  Tried everything. So I let them download and then deleted them.  Now when I try to delete them from the deleted items folder they won't go. the error is "UID store failed"  this is slowing down my computer. how do I get rid of these deleted items?