One reason for Signal app's popularity is its ability to send messages that are deleted from the app after a preset time period, but that may not always be the case, a security researcher warns.

The Mac version of the app displays recently received messages in the macOS Notification Center, but because of the way Macs handle notifications, the messages linger on the recipient's notifications bar even if the message is set to self-destruct using Signal's timer, Motherboard reported Wednesday.  The notifications display the sender's name and the message's content.

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