Email forwarding amounts to ritual gift exchange

Forwarding a genuinely amusing or interesting link to a friend, for example, shows that you are thinking of them and are aware of the sort of content they like, Gross says. But passing an irrelevant or out-of-date link on to contacts can be annoying, thus lowering the sender's social status in the recipient’s eyes.

Or “Why you should never forward anything that already has 10+ people on the cc: list.”