You can go to the trash can in your mailbox and restore this file, or mark this email address as a white list. Next time, the files sent from this mailbox will not be automatically sent to the garbage station

Build a Whitelist in Address Book I assume, yes?????

OK, all of a sudden I am seeing other emails that I know are in my address book and they are now going to Trash. Think there are two problems here. One, why are emails that routed properly a few days ago suddenly going to Trash? Two, if they are in Trash; why can't I move to Inbox and have them remain in Inbox(don't return to Trash)

Will add these more recent ones to Whitelist a bit later since I receive mailings from them more often. BUT, I should not have to build a work around to take care of a problem.

Have email in Trash; want to move to Inbox; I move it to Inbox, short while later it goes back to Trash; WHY??

But how did it get there? Silly but entirely relevant question. If your account is IMAP and the mail is there because the mail server is programed to trash old mail or mail that meets other requirements, or you have deleted the mail on the server than Thunderbird will synchronize to the server state. In the first two cases I would expect the server to immediately respond by deleting the mail again hence the magical return to trash.

OK, I just compounded my problem. Changed the rules to IF not in my Address Book move everything to Trash. It moved almost everything in my Inbox to Trash. Yes i am Imap. Thought that I entered everything as POP. So my immediate problem is to try to save what was in my Inbox; if I really need it saved. Will let you know, don't need to tie you up here if I hopefully can figure out how to undo the mess that I have created. Thanks.......

open the trash, select one entry and press Ctrl+A Drag your trash emails and drop them in the inbox and pray. Most if not all should return (issues arise with sync timeouts over huge numbers but a few hundred is generally not an issue). But leave Thunderbird open for an hour or more to allow the back and forth syncing with the server to stop.

I should know better than to be trying more than one thing at a time. But between what you told me and me simplifying my rules and filters, at the moment the problem seems to have gone away. What bothers me is if it was any of my rules or filters it is not like I am in there playing with them to have created the problem; so bottom line I am not 100% sure what fixed the problem. Thanks for your suggestions/fixes.