I'm on macOS Mojave, Mail is version 12.4.
I've just realized that
delete is deleting (ie irretrievably removing from my machine and server) my emails instead of moving them to the trash. I want my emails to go to the trash so I can recover them later if needed. I would like to change the behavior of that keyboard shortcut, but I doubt that's possible on macOS so I'd settle for adding a new shortcut. However, I can't figure out how to do that.
What I've tried
I've tried changing the mailbox behavior, which is what others have suggested, but there doesn't seem to be an option (see screenshot below). I'm using MailFence if that's important.
I've tried adding a keyboard shortcut specific to Mail (see screenshot below), but it isn't doing what I want. Note that I have tried to name the shortcut 'Move to Trash', 'Move to trash', and 'Move to Trash Foo' where 'Foo' is the mailbox description and when I use the menu to move a message into trash I select Message -> Move to -> Trash -> Foo
deletebutton now sends mail to the server's trash. I can confirm this by going to the trash can on Mac Mail, and by going to mailfence.com, logging in, and looking at the trash there. I did not change anything and yet it's working. I may have deleted it and re-added it for an unrelated issue, so maybe that solved it?