From ABC via Foreign Policy:

In a Dilbert-esque faux pax, a Taliban spokesperson sent out a routine email last week with one notable difference. He publicly CC'd the names of everyone on his mailing list.

Potentially a lot more consequential than a bogged down mail server.

 :O

 Gotta catch 'em all!

 Please take me off this list. Please. I beg you.

Seriously.

 

You can put whatever headers you want when sending the message over SMTP (although it also adds its own headers), so it would also be possible to add names into the CC list which are not actual recipients, or which are not even valid email addresses.