Click on Tools->Account Settings, and In "Server Settings" (above the "Copies & Folders" category), there is a sub-section in the middle of the window called "Server Settings," (yes, kind of redundant, isn't it?) and under "Check for new messages at startup" and "Check for new messages every X minutes" there is an option titled "When I delete a message". Here you can specify whether it gets moved to a folder (and which folder on the server, marked as deleted, or erased immediately. Check to see what you have configured here.

Norio, thanks for your intelligent and clear reply. Thunderbird 38.1.0 does not have that "When I delete a message" at all anywhere in the Server Settings or "Copies & Folders"

Anyway, I have subsequently discovered that new emails received after the upgrade to 38.1.0 do automatically go into "Trash" when deleted. Only emails that were in the Inbox and Sent folders before the upgrade disappear....who knows where? So no problem the old emails I will drag into Trash and not worry. The new ones are behaving normally.

Thanks again for trying to help me.

Hi qderf, I'm glad you were able to figure out a workaround. However, I'm surprised that you couldn't find a "When I delete a message..." section in your Server Settings dialogue. I too am using version 38.1.0, and I have this option available (on both IMAP and POP3). I'm using Windows 7 and 8.1--are you by any chance on a Mac operating system? If so, I guess the dialogues are different. Anyway, take care and good luck. Norio

Hi Norio, I am on a Dell Precision M4700 running W 7 with all updates and newly downloaded (last week or so) & Thunderbird 38.1.0 Believe me, I have been all over the "Account Settings" and, for instance under "Junk Settings" there is the expected Move new junk to the "Junk Folder" on:...etc But no where anything similar for Trash. Anyway now when I delete a message in from my inbox, it automatically goes into my Trash folder...so that is working as I want it automatically.

Thanks for your interest.

fred

The trash folder option only appears on an IMAP account. it is not an option for POP since POP is kept on the local computer and you do not get to make the choice to have the folder elsewhere.

That explains it Thanks Airmail. Why the messages from before the upgrade just "disappear" when deleted will remain an unimportant mystery to me.

fred

Ok, I am running version 38.3, and I can not find the place where it asks what happens to a deleted message. Can someone please tell me how to find it in my version. It seems that they have disappeared only recently. And in trying to find the recent deleted messages, they did appear, but not individually, but in a list of emails.

Very confusing!