Communication: Type 1 Remailers

Type 1 (or "Cypherpunk") remailers added the ability to chain remailers together.

A message would travel through a number of remailers on its way to its destination, using random delays.
To figure out who sent a particular message, you would have to backtrack through all the remailers in the chain, getting them to look at their logs and tell you who the previous remailer was.
But they usually don't even keep logs!
These are still vulnerable to active snooping while messages are being sent.
Attackers can use correlations of size to watch messages passing through the remailer network.