[ietf-dkim] What's a replay?

[Jon Callas]

Forgive me my ignorance, but I don't understand what's meant by a 
replay.

There are three things that I think of as a replay. None of them are 
affected by features like "user-level" keying. Furthermore, none of 
them are to me distinguishable from a forwarder (like .forward).

So, obviously, I'm missing something. Can we simplify this down to a 
short description of what a replay is. Quick little scenario.

For example, here's one thing that I could envision being called a 
replay:

Advertiser.com sends a legitimate mail to Alice. Alice takes that mail 
and sends it to 50 million of her closest friends. These 50 million 
people get angry at advertiser.com.

What else? What's a replay?

	Jon