The right button should just produce a normal pop-up or "context" menu. It shouldn't directly do anything to the messages.

No pop-up or "context" menu (not sure what this is) appears, The email totally disappears, it is not any where that I can find.

I forgot to say thank you for responding. This situation has just gotten so frustrating that I finally decided to ask for help.

To diagnose problems with Thunderbird, try the following:

• Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.

Thank you. I disabled all add-ons, I did not know I had any. Everything seems to work fine now. I still wonder where the missing emails went, but I just right clicked on a test email and the response was what Zenos predicted and the email did not disappear.

Problem solved.

If you do the re-enabling process until you work out what caused it, then we might be able to postulate where they went.

Since I did not know I had any add-ons, I have no idea what to re-enable. For the "lost " emails, I found other ways to get the information and send it to myself. At this point at least I am very happy, and no longer frustrated.

If I see a hint at adding an add-on, I'll test the right button and if it disappears my email again, I'll disable the add-on.

Thanks again, Matt.