I wouldn't want to give a recommendation for a certain anti-virus software. You may check this site and pick the one which is less likely to cause problems. https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues

In general, it is recommended to create an exception for the Thunderbird profile folder, so that the real-time scanner won't touch it. Check this article for more information on the profile location. http://kb.mozillazine.org/Profile_folder_-_Thunderbird

Thanks for your input, Christ 1. I went through the pages you suggested and played at length with avoiding the TB profile in NAV. After that didn't help, I spent more time on the web and decided that maybe the later versions of TB were a problem, so I killed the TB I had and have reinstalled an earlier version, in this case 31.1. Still no luck. Might go back one more revision of TB. I sent a memo to NAV about all of this, and heard nothing from them til they sent a survey asking if their response had helped. Great fun.

I had and have reinstalled an earlier version, in this case 31.1.

I think you're on the wrong path. Going back to an older Thunderbird version isn't a solution, and it will cause problems in the future.

Please also follow the advice given above. https://support.mozilla.org/en-US/questions/1087636#answer-791155

Thanks Christ1 for your follow up.

I just fixed the bug that was caused by a filter at DSLExtreme.com which handles my email. They had a filter set up that favored junk stuff. Why it elected to filter my stuff from one particular source I don't know, but with their tech support I was able to set up the filters to allow the email I wanted to pass.

I appreciate your help. Now to set all the stuff back to normal again .... r

Good. Can you then mark the thread as 'Solved' please? Thank you.