Anonymous remailers are specific software (Reliable,Mixmaster, Freedom, Ghio..),
running on machines operated by unpaid volunteers.
End-users may build their messages by hand,
but will gladly turn to specific software (JBN, Pidaho, QuickSilver...)
Their purpose is to remove any link (identification) between the messages they receive and the ones they reemit.
Ensuring,
if properly used,
total anonymity for their users.
For the best and for the worst.
(Cf:
Why use Anonymous Remailers?)
The process is to remove *all* Header (with its various identification marks) from inbound messages
and to reemit an oubound message bearing a different Header (with new identification marks).
(This message will be a mail or a post via NNTP or a m2news gateway).
To fool possible traffic analysis,
many messages may be merged and then split ('mix' technology, 28K
messages)
messages may be resequenced or delayed
.....
Of course, no cross-reference table is created nor kept
between inbound message-ID(s) and outbound message-ID(s).
The Body of the message received by the remailer is normally encrypted with a public-key
algorithm.
It holds:
-directives to the remailer on how to reemit the message (@, subject...)
-the message to be reemitted on next hop