Before chaining one's messages one must have an understanding of
middleman remailers.  A middleman remailer ("middle" in its cap
string) is one that always adds another hop to any message that is not
already en route to another remailer. Example: If you send a message
to recipient <my_coworker@entrust.com> through middleman remailer
Georgia Cracker <remailer@gacracker.org>), Gacracker will send it to
say, <remailer@dizum.com>, with instructions to deliver to
<my_coworker@entrust.com>.

This behavior demonstrates what is known as smart middleman. All
Reliable <http://www.bigfoot.com/~potatoware/reli/> remailers that are
running in middleman mode are smart.Check the remailer-conf file to be
certain just what kind of middleman behavior to expect. Now, back to
chaining.

Chaining is using more than one remailer to send your encrypted
message. Basically, you send a message to remailer A with instructions
to send it to remailer B, which in turn finds instructions to send it
to remailer C, and so on, until the final recipient receives the
message. The intention is to obfuscate the origin of the email and/or
(with the help of encryption) the content of the message body. At any
given point on it's route, such a message will reveal only where it
came from and where it is going. If the message was not chained (only
one remailer was used) then that remailer operator or a successful
traffic analyst can know the true source AND destination of the
message. Not good.