It turns out that I've just scratched the surface, though: If you send e-mail from a mobile device like a BlackBerry or iPhone and you use those automated mobile signatures, it can be worse than that.
Recently, I was minding my own business, reading a post on Lifehacker about how mobile e-mail signature might not have the effect you intend. And that reminded me about how dangerous those mobile signatures are in a business environment -- in fact, the problems go far beyond what Lifehacker suggests.
Specifically, we're talking about signatures which get automatically appended to the end of messages and say things like "sent from my iPhone" or "sent from my Blackberry." Seemingly innocuous, they are generally intended (I suppose) to say "I'm writing this on the go, so the message will be short and might have a few typos in it."
Lifehacker says they have an unintended consequence, though. They can annoy recipients, especially when the short, typo-riddled response is only cursory and addresses only a small aspect of the original e-mail. It's like you've appended a Get Out of Jail Free card to the end of your e-mails to excuse bad e-mail etiquette.
Personally, I think they have at least two other serious problems:
They're snobbish. Sent from my iPhone is the e-mail equivalent of My other car is a Lexus or (if I can extend the car metaphor) Baby on Board. It's easy to interpret the signature as a an attempt to broadcast a status symbol, whether you intended it that way or not.
They can poison business relationships. A friend mentioned to me the other day that he just bought an iPad and send his first e-mail with it. He sent it to his boss, and then discovered, to his horror, that the iPad defaults to attaching the Sent from my iPad signature to all messages. Did I mention that he works for a company that has a somewhat adversarial relationship with Apple? Do you know the business relationship all of your partners have with Apple, RIM, and Google? If not, perhaps broadcasting the technology you use is not a smart idea. Unless you think it's cool to park a Toyota in a Ford factory parking lot.
Photo by Cavin