You can only restore an email from trash if you had deleted it individually and not used the 'Remove All' function.

To restore mail,

1. Click on the 'Browse Space' link at the top of the page.
   
   
2. Go to the tab 'Space Admin'
   
   
3. Click on 'Trash' in the left panel. A list of pages and emails deleted from the space are displayed.
   
   
4. Click on 'Restore' beside the email you want to restore.

To view this mail, you will have to go the 'Mail' tab under 'Browse Space'