Soft Deletions stopped working

Hi:Wondering would anyone know what I could try here? When a user goes’ to delete a mail in his inbox, he now has to press F9 and say “yes” each time he goes to delete a message. I’ve tried turning off and on soft deletion. Compacting his mail file with the -C option and fixup. This used to work for him but just stopped recently, Soft deletions work fine if I open his mailfile on my PC. Seems to be an issue just on his PC. He has editor access to his mail file an it used to work. Any ideas on what I could try here? thanks