Why do people leave their signature "Sent from my iPhone"?

Signatures have existed preconfigured on smart phones since the beginning of time. The iPhone did not by any means change the game here. Have you never seen "Sent from my Verizon Wireless BlackBerry" before?

By default, most users are not savvy enough to realize that the signature is something that can be modified and/or removed completely.

In any event, I modify my signature to read: "Message sent from a mobile device, please excuse typos and brevity". This is a completely legitimate practice (although subjective at the same time) in that if I am replying to an e-mail, I want the recipient to know that I am not cutting them off short or am attempting to be rude - particularly if my responses to said individual are typically thorough with details.

If I am on a train ride and take the time to write a 2-3 paragraph e-mail on my mobile device, I will simply just backspace the signature and be done with it.

I am not attempting to portray a snob when I leave my signature in tact. Quite the contrary -- I simply want to get a message across to someone who took the time to write me an email in a timely fashion without offending them if my response lacks proper email etiquette and length.

I leave the "sent from my iphone" signature just to bug people who get bothered by things like that.

I leave it so people can understand why my responses are so brief.

I change mine to "sent from phone" or something brand-neutral like that so any terse language or misspellings might be excused by the recipient.

I added my phone number after '--sent from my iPhone' so people can call me while I'm on the go if they need to. I feel the signature works for me because it reminds people about brevity. The only stuff I answer from my phone is important, anything else can wait.

I guess I could change it from 'iPhone' but I don't see the point. Do I need to pretend I don't use an Apple device?

The EVO is worse. It's "Sent from my HTC EVO 4G on the Super Awesome Sprint 4G Network - The World's First NOW! Network!1" or some ultra-long BS like that. I might be exaggerating a bit, but not much. I guess it's an multi-vendor arms race.

I leave it because it lets people know that I'm out and about, and I'm not really going to be able to do much in terms of solving problems until I get back to my laptop.

Why do most VCRs still say 12:00? People generally only change stuff that interests them or bugs them, and for most people this occupies neither category.

If you really wanted to show off that you had an iPhone you'd probably at least want to say: "Sent from my White iPhone 4, 32GB with Retina Display" ;-)

But seriously, I imagine most people who have this signature in their mobile emails have no idea how/where to change or disable it. The other reasons you cite are legitimate possibilities, but probably to a much lesser extent.

The iPhone component - or "Verizon Wireless Blackberry", whatever it is - infuriates me.

I changed my mobile signature on my Incredible to say "Sent from mobile." That way, people know why the spelling might be bad, but I don't feel like I'm being used for free advertising.

I have a friend who changed her gmail signature is "Sent from my iPhone" for reason #2.

I've had to "reset" my iPhone a number of times. Sent from my iphone is one of the SMALLEST configuration details I worry about when resetting it.

This somewhat seems like someone is overly reading into something.

I've had my blackberry for over a year and send emails from it daily.

I never knew before now that it had a signature attached to it. Now that I know, I have no idea how to change it (though trivial, I'm sure)

I rebranded mine to help build MY business - not Apple's.

Summary: "They want to show off that they have an iPhone. They want to be excused for typos or short sentences"

I have a friend who used 'Sent from your iPhone' for a couple days when they announced the browser exploits.

Mine says: "Sent from my iPad Nano" People always get a chuckle out of that, so I leave it.

Because people leave "Sent from my Blackberry" and "Sent from my Verizon Wireless yada yada"

Inertia

Probably cause most people don't send emails to themselves and know it's there?

i usually reply only when there's a problem and i want the people to know i'm not at the computer so there's not much i can do :)

When I asked my father this, he said that he does this so his clients can see that he's engaged in their business even when it's inconvenient for him.