Often you select 'Other' and choose the 'Sent' or 'Sent items' whatever the imap subscribed sent folder is called for that account.

Is there a particular reason for needing to change the setting?

Do you have any product like CCleaner working on your computer that cleans up files ? Note some Anti-Virus products can also perform similar cleaning up actions. If yes, please make the Thunderbird profile folders exempt. Programs like CCleaner can remove session etc files and cause a real nuisance.

Thanks for such a quick reply. When I set up the account years ago I didn't know what I was doing. I have a number of accounts now and want to make the settings consistent. In addition, I have recently read up on how Thunderbird labels emails to give me a better idea how to better manage the large volume of emails I have from years past. No cleaners or anti-virus programs being used. Using a Mac with Mojave 10.14.4 and Thunderbird 60.6.1 (64bit).

re : I have a number of accounts now and want to make the settings consistent.

Settings do vary. Pop mail accounts use 'Other' if they are Global Inbox (deferred accounts) otherwise use eg@ 'Sent folder on' pop mail account. This is the same for all the settings in the 'Copies & Folders' section.

Imap mail accounts may need to use 'Other' to select a subscribed folder on an imap mail account, if the eg: 'Sent folder on' is not working correctly.

If an account is working then changing settings is best left alone, but...... Q What type of account are you talking about? Q Is it a POP or an IMAP mail account? Q If Pop, is it a deferred account, one that is set up to use a 'Global Inbox' which is usually 'Local Folders' Inbox so all incoming emails show up in Local Folders mail account? OR does the Pop mail account use it's own set of folders and displays in the Folder Pane?

Regarding large volumns of emails from years past. Pop mail accounts are generally set up to use 'Archives' folder for when you wish to archive an old email. Archive setup info:

• https://support.mozilla.org/en-US/kb/archived-messages

As emails are stored on your computer remember to create a backup periodically.

Imap may also have an archive folder , so after moving a laod of emails, you can choose to unsubscribe from seeing it if desired. Note: Gmail store and archive all emails in the server 'All Mail' folder.

At some point, you may need to gain space on the server if your quota is being used up by ancient emails, so downloading full emails for offline use may be useful, then get copies into 'Local Folders' mail account for storage. You can create any number of suitably named folders to do this. Once you have copies in Local Folders mail account (if you can read them in offline mode then you have a good copy), you can remove/delete emails off server to gain space.

Imap accounts store emails on the server. You cannot rely on any imap folder being a backup as those folders synchronise with server to show what is on server. Emails in 'Local Folders' mail account are stored on your computer. You should still create backups of your Thunderbird profile folder as the server is only the one copy.

Thank you for taking the time to give some great info. The accts are all imap since the beginning. FYI, I am using the archive feature and deleting emails directly from the google account which is another question. Why won't deleting emails in Thunderbird delete them in the google account? They just seem to reload in Thunderbird! I delete them from within google mail and it takes care of the problem. Hate the extra step though.

As for my original question, you mention "Imap mail accounts may need to use 'Other' to select a subscribed folder on an imap mail account, if the eg: 'Sent folder on' is not working correctly." If that were the case shouldn't the other box be greyed out? It seems to give me a choice but won't keep the setting. Has anyone else experienced this?

re : Why won't deleting emails in Thunderbird delete them in the google account?

Gmail stores all emails in the 'All Mail' folder. The reason you can see them in the eg: 'Inbox' is because gmail applies 'labels' to emails. It works like a type of tag or virtual filter, so you can see emails in the expected folder format. If all labels are removed then the email is archived in the 'All Mail' folder. It is not actually deleted off server. If you delete and do not put the email in the server gmail Trash folder, then only a label is removed. If the email is deleted and put into the gmail Trash folder, then gmail will auto delete the email from Trash approx after 30 days. It will also delete the email from 'AllMail' folder.

This means you need the deleted email moved into the gmail server Trash folder when you click on 'Delete' button. This can be done via all Imap mail accounts, but not Pop mail accounts.

First, you need to subscribe to see the gmail Trash which may also be called 'Bin'

• Right click on imap mail account and select 'Subscribe'
• Click on 'Refresh'
• Select the server 'Trash/Bin' folder
• click on 'Subscribe'
• Click on 'OK'

Then you need to have the imap mail account 'Account Settings' > Server Settings' set up : When I delete a message:

• Select 'Move to this folder' and choose the gmail Trash Bin on imap mail account.

Also make sure the Inbox is auto compacted. Under 'Message Storage'

• select 'Clean up (Expunge) Inbox on exit.'

click on 'OK'

Restart Thunderbird