Trash / Bin Mail Folder in iCloud

Erase deleted messages

Mail erases deleted messages at the specified time. Select a setting other than Never to avoid exceeding storage limits set by your email account provider.

If you selected None for Trash Mailbox, you can have Mail permanently delete messages automatically.

If your email account provider sets up the server to delete older messages, the messages are deleted regardless of how you change this option.

Change Mailbox Behaviours settings in Mail on Mac - Apple Support

Note : prefer to do a screen sharing with apple support care advisors Contact – Official Apple Support

Contact Apple for support and service - Apple Support

Most probably the Mac OS is corrupted .

See the article Create or delete mailboxes in Mail on Mac - Apple Support

WARNING: Deleting a mailbox permanently deletes the mailbox and its contents (including other mailboxes), and can’t be undone.

The deleted mailbox folders with mails inside them don't move to bin .

Enter in user library , right click over the mail folder and click on copy mail .

Again , on the empty desktop screen right click on the desktop screen and click on paste item , the entire mails are copied and pasted in the V10 folder , the original V10 folder will remain intact in user library .

Make sure you don't drag and drop the V10 folder directly to desktop screen before copying and pasting this will corrupt mail application .

The Mac is connected to an external hard drive .

 1 ) Enter in user library ( click on finder take cursor on top menu bar > Go then Hold option key and click on library ) > select mail and right click on copy mail and then right click on empty desktop and click on paste item , the V7 folder will be saved on the desktop .

Did you saved all mails in V7 folder and dragged and dropped to an external hard drive , if so this will occupy hard drive space .

For latest version of Mac the V7 folder will be on higher side say V10 ....

The V10 folder is on the desktop screen , right click over it and move to bin , restart Mac and empty bin , the folder and its mails are still saved in user library , the desktop V10 folder was just a second copy of it , as you created it on the desktop , its optional you can save this folder to an external hard drive and then disconnect the external hard drive .

Note : never drag and drop V10 folder directly from user library to desktop screen , the mails are to be copied and pasted , as described in previous post .

checkmark empty trash automatically ( turn on ) and delete junk mails .