If you have ever received or sent an email via an iPhone then you should be familiar with the “Sent from iPhone” signature that all mails are automatically signed off with.
It was a not so subtle way of letting everybody know that you owned an iPhone back when they were super expensive and rare, so basically it let you brag about your fancy new iPhone.
But the signature is now making a return and being completely justified. It has now turned into a disclaimer and apology beforehand for abrupt poorly composed emails, filled with grammatical and spelling errors.
The signature lets people know that the particular email in question is not a representative of how they actually respond.
The whole argument is cemented by a paper titled Sent From My iPhone: The Medium and Message as Cues of Sender Professionalism in Mobile Telephony, written by researchers Caleb T Carr and Chad Stefaniak.
Before the iPhone even existed BlackBerry offered its own personalized signature which is now all but forgotten. After all these things have a limited life span, constrained by the next upcoming innovation.