Deleting multiple email messages

⇧⌘⌫ (Shift-Command-Delete)... then Enter.

This key combination will prompt you to acknowledge deletion of mail in all Trash mailboxes. Pressing Enter makes it so.

Additioinally, here's another that I find very useful for emptying the Junk mailboxes: ⌥⌘J (Option-Command-J)... then Enter.

TIP - Very many actions can be commanded by the keystroke shortcuts that you can find next to the commands in the menus. Learning these can increase your speed and productivity appreciably. 😉

Hello KVHOOSER34,

In Mail, select the Trash folder and use the key combination command + A to select alls emails in the folder. Then press the delete key.

In the Mail app, click on Mailboxes in the menu bar, then choose Erase Deleted Items. You can select all accounts or specify which one you want to target.