Clarity Strategic^TM

The signature file is one artifact from the days of Usenet that persists today. It's your online business card - some people liken it to a letterhead - containing (hopefully) enough information about you to allow people you've never met to distinguish you from everyone else in the world. Why does it work this way?

Primarily, it's because people are used to finding that information in a certain place: at the bottom of your e-mails. 99 times out of a hundred, you may ignore sig files in all the e-mails you get, but that hundredth one may be the one where you need to reach out. You expect then to find the 800 number, or maybe in this case the Web site. I've asked about sig file habits on LinkedIn, and in several dozen very interesting answers, I've found some of my own habits reinforced, and a few wrinkles I'd never considered. First, the old:

• Use ASCII characters only. There are several reasons for this, but chief among them: not everybody uses an HTML-enabled mail client; you may find you want to transplant that ASCII text, and ASCII characters can go anywhere with nothing funky showing up unexpectedly.
• Include your contact information. That means any means you might actually USE for people to contact you: address (or at least geographic location), phone number, Web site, Facebook, Twitter, LinkedIn, etc. And remember that can all be abbreviated, because you want to also...
• Keep it to four or five lines at most. Too many lines, and nobody will read it at all. The four lines is a rule of thumb adopted by countless thousands in the Usenet days, and it is still a mark of simplicity.
• It's OK to include a pithy quote. And many people do. Of course, if you do, that has separate rules of thumb to follow. I contend that clean humor, especially the self-effacing kind, is the best policy here. Though you might even be better served by a memorable tagline about your business.
• Don't let it dominate your content. The items above give you some idea how, but there is also this: the sig file should be ready to go in advance if the message is important, and it should not in any way distract from the message. How might you tweak it for a certain customer or prospect? That's the question to ask.

And now, the new:

• The call to action! If you are reaching out to a prospect, let that signature suggest to them their next move. If your content is good, there is no need to wait.
• Be careful! One reader writes

  If someone spends more email real estate selling me than talking to me, well - it won't be long before I use Outlook's filters to drop their emails in the spam folder automatically.

After writing this, I've decided to start using sig files in LinkedIn Q&A articles as well as e-mail! :-)