[Zimahl]

In case you signed up using your work email, like practically everybody does

1) Why would anyone use a temporary email to sign up to a social service?

2) Why would anyone use their work email for a job networking social site knowing full well that work emails are not private?

[Angostura]

There are a lot of people who use their work e-mails with LinkedIn because LinkedIn provides a useful adjunct to their actual work. A company that I used to work for, for example had a link to each person's LinkedIn profile on their biography page. The testimonials they received on LinkedIn were worth rather more than the ones that might be put up ib the business' own site.

[tedunangst]

Because your invitation came from a coworker who used, you guessed it, your work email.