Missing e-mails on EVO

Out of the blue, I have started to have e-mails disappear on my HTC EVO. I've exhaustively looked at the settings on the EVO and in Outlook. Now, I suspect perhaps a setting in Mailwasher Pro 6.51 may be the problem! The e-mails on the EVO seem to go away after I have successfully downloaded and viewed in Outlook and on the handheld. They disappear on the EVO after I then mark, and execute, all e-mails for deletion in Mailwasher.

By the way, this started happening after I installed K-9 e-mail client on the EVO. However, I have gone back to using the standard EVO e-mail program. Having same problem with both programs. Wondering if maybe I should uninstall K-9.

Repeating though, it seems to be connected to deleting messages from Mailwasher after they have been successfully downloaded & viewed.

Just sent an e-mail from one of my pop accounts to my gmail account. Allowed it to pass through Mailwasher ...downloaded and viewed it in Gmail on PC. Then, marked it for deletion in Mailwasher...ran it through....and it disappeared in Gmail on PC. Solidifies my suspicion it's a Mailwasher setting...not an issue with EVO, Outlook, Gmail.