Add test for mail deletion with invalid mail id
Add test for mail deletion with invalid mail id

- Issue #511

pixelated-project/pixelated-user-agent,pixelated-project/pixelated-user-agent,pixelated/pixelated-user-agent,pixelated/pixelated-user-agent,pixelated/pixelated-user-agent,pixelated-project/pixelated-user-agent,pixelated/pixelated-user-agent,pixelated/pixelated-user-agent,pixelated-project/pixelated-user-agent,pixelated-project/pixelated-user-agent