pp. Altering one's return email address in an effort to thwart companies and individuals who send out unsolicited commercial email.
1999
A guide to email spam describes safeguards and filters which the average user can employ on his own behalf, including address "munging".
1998
Many solutions have been suggested to manage the problem of Internet abuse. These methods have varying degrees of success and utility. I argue that the practice of address munging is in itself a problem.
1997 (earliest)
As long as we're getting spammed with UCE, especially when they are culling our addresses from our posts, people are going to munge their address in an attempt to prevent that. If you want the address munging stopped, stop the spammers.
If address munging is performed, then all addresses contained in all address header-lines must be munged. It is expressly forbidden to perform address munging on the source message and without performing address munging on every address header-line. Further, it is expressly forbidden to munge some, but not all, of the addresses in any address header-line. All addresses in all of the message's address header-lines must be address munged.