Desktop version:
If you have inadvertently deleted a mail thread with another user, you may restore it by going to your “Trash” folder, which you can find in Mailbox tab. There, you may select the thread you wish to restore and click on the “Restore from Thrash" button.
Mobile version:
If you have inadvertently deleted a mail thread with another user, you may restore it by going to your “Trash” folder, which you can find in Mailbox tab. There, you may select the thread you wish to restore by ticking it and click on the red “Restore selected" button.