One way to get the message back is to return to the Mailboxes screen (tap the Back button in the top-left corner of the display), open the right mail account, tap the Trash mailbox, then scroll through and look for the message you accidentally deleted. If you get a lot of e-mails, finding the right message could be like looking for a needle in a haystack.
Want to undelete an accidentally trashed mail message? Just give your iPhone a shake.
Luckily, there’s a much easier way to recover deleted emails, assuming you catch your mistake quickly enough.
The secret: just give your iPhone a shake.
When you do, an “Undo Trash” pop-up will appear. Tap “Undo,” and the message you just deleted will jump back into your Mail inbox.
Yes, it’s the same trick as shaking your iPhone to undo your typing—except in this case, the action we’re undoing is trashing a mail message.
But there’s a catch
However… the iPhone’s shake-to-undo feature only works for the last action you took.
That means if you want to recover a deleted email by shaking your iPhone, deleting the message must have been the last thing you did. If, instead, you trashed an e-mail and then began typing a new message, shaking your iPhone will only delete what you just typed, leaving your deleted message lost in the trash.