It may be telling that I want to keep typing .signature instead of signature -- I may be a bit old school. But I've also given up on keeping HTML out of signatures (and email in general), so I guess I'm adapting somewhat.
Regardless, the topic came up at work today about what we should have in our standard corporate signature, and here are the points I replied with based on my 20 years of having to read email...
- The content of your email should be more interesting than your signature -- don't distract from the email content with a flashy signature
- The postal address should be on our website, not in email signatures
- If nobody has faxed you anything in the past 6 months then probably not worth it to include a fax number, put it on the website too
- Be aware of the size of images you're including, and that attaching them to email adds another 1/3 because of encoding
- Signatures should start with dash-dash-space
(-- )then a newline, then the rest of the signature
- Signatures should not exceed 4 lines, unless a legal disclaimer is required
- If you're going to include an email address make it clickable; probably the same with twitter, link to twitter.com/whatever
- You should include whatever phone numbers you actually answer / are expected to answer