Funny from address for mailing list message
Chances are this is a VERP message ... VERP stands for "Variable Envelope Return Paths" and it's one of the ways the list software (Mailman) makes sure that the person it's sending to is actually receiving the message.
It does this by altering the "Sending" address to include the actual recipient information.
That way, when the message bounces back to the sending address (a special address that is attached to a program that interprets the bounce text), it is able to figure out exactly who it sent the message to in the first place.
The funny address will look something like this: firstname.lastname@example.org
More information about VERP messages can be found at: http://cr.yp.to/proto/verp.txt