One way to do this is to use soft deletes. This will get the e-mail out of your inbox instantly upon hitting “delete”, but it is still around in the trash view, just in case you deleted an e-mail accidently. You can set this property in the database properties popup at the bottom of the last tab (beanie tab).

A second solution is to select the e-mail then press Shift+Delete.
This deleting method is not reversable. Mail will be gone with no undo.

Use soft deletes is the best solution.and if you deleted the mails bymistake then too you can get it by pressing shift insert.