How to delete a message:
The authority can still receive and respond to the message you have sent, even if you delete it from the Sent folder.
When the message is in the Deleted folder, you can restore it to its original folder by opening the message and pressing the Restore button at the end. The button will indicate to which folder the message will be restored.
If the message is the first message in a message thread, it will be removed from the Deleted folder only when all newer messages in the thread have been deleted.
It is not possible to delete several messages at once.
How to find the Deleted folder: