deleted emails keep returning

Ok here the problem the user is using incredimail. He checks his mail everyday one day he cam ein and there was 93 new messages. He deleted these messages and minutes later they returned. I edited the options to empty the deleted folder upon exit. I then deleted all of the messages again, then exited the program, the deleted folder was emptied. I opened the incredimail again and about a minute later all of the e-mails came back with the original sent date and times. Please help, I email incredimail already and they still have not gotten back to me.

 

This incredimail Client. Does it have a option to "leave a copy on the server" like other email clients do and if so is that checked? Also if you switch to a different email client does the same problem occur?