I can't delete emails on my desktop email

On my desktop mai, when I try to delete old emails by sending them to the treash, I get this message "The message could not be moved to the mailbox "Trash-shaw" "The destination mailbox-shaw does not allow messages to be moved to it". I have the trash garbage can icon there, but my have deleted a sub trash folder or something and now I can't delete. Can anyone help me? Thanks.