If you have deleted messages from the folder, go to "Trash" and use the search form who is located on the top corner to find the necessary deleted posts. If the letter was found, restore it to folder "Incoming”.

If you delete messages from the folder "Trash” (or repeatedly press to clean the trash)  deleted messages of the last seven days can be restored back.

If you clear the entire contents of a folder for example the Spam folder or any other in this case, letters are deleted immediately without trading in Trash. These letters can’t be restored.