At the end of last month, to the undoubted delight of many users, WhatsApp began rolling out a long craved-for feature: the ability to "unsend" those messages that you almost instantly regret as soon as you hit the Send button.

The feature, which was rolled out on the latest versions of WhatsApp for iOS, Android, Windows Phone and desktop, simply requires the regretful messenger to tap and hold on the offending message, choose "Delete" and then select "Delete for everyone".

As long as you did this within seven minutes (and the recipient was also running the latest version of WhatsApp) the message would be successfully deleted, the company promised.

But, if there's one thing we should all have learnt from our years on the internet, once you say something somewhere - it's very hard to take it back and pretend it never happened.

And there's good reason to not get too excited about WhatsApp's new "Delete for everyone" option.

Although it promises to zap the embarrassing messages you've already sent to one of your contacts, the truth is that they may not actually be gone at all.

Within days of the new feature being incorporated into WhatsApp, the Android Jefe blog found a way to read "deleted" messages.

On Android, WhatsApp messages are stored in the device's notification list - regardless of whether they are subsequently deleted by their sender or not. All a user has to do if they wish to remind themselves of a "deleted" message that they have been sent, is check the notification log where the first 100-or-so characters are stored.

If that's too much of a palaver, there are even apps in the Google Play store that will provide a simple clickable link to to the notification history.

It's important to stress that Android Jefe did find some limitations in its method of viewing "deleted" WhatsApp messages:

  • Only messages that have already been seen or interacted with can be retrieved from the notification log. This does include any interaction with a WhatsApp notification, so the message itself does not have to have been opened.
  • Only text sent via WhatsApp can be "undeleted" in this way, and even then it is limited to the first 100 characters or so. The notification log will not contain any images that you were sent.
  • Only messages that generated a notification will have created an entry in the notification log - logically enough. In other words, if you were chatting on WhatsApp at the time the message was sent a notification will probably not have been created.

Nonetheless, it feels like this discovery is a timely reminder for all of us that once we send a message it is effectively out of our control. Always think hard before pressing "Send"!

Oh, and while we're on the subject, Android Jefe also found a way to "delete" WhatsApp messages up to 7 days (rather than 7 minutes!) after they were sent, by simply fiddling with their smartphone's clock.