Message deleted from Outbox is deleted from recipient Inbox.

1. Log in to the forum
2. Create and send private message to User2
3. Go to Outbox
4. Click on Subject of sent message to open a message
5. Press Delete button
6. Press OK in confirmation message and go to Outbox

AR: Deleted message still in Outbox.
Delete_from_Inbox status is set in DB in Private Messages table; the message isn't shown in the User2 Inbox.
ER: Message should be deleted from Outbox and still shown in User2 Inbox.