The plain text version is regularly posted to comp.mail.misc,
comp.mail.elm, comp.mail.mh, comp.mail.mush, comp.mail.pine,
comp.mail.zmail, comp.answers, and news.answers.  It's
in digest format which means that you may be able to use your
newsreader to easily move between digest items (e.g., nn uses G% to
burst a digest and trn uses ^G to jump to the next digest item).

The plain text FAQ is also available through:

Anonymous FTP:
 ftp://rtfm.mit.edu/pub/usenet/news.answers/mail/

Email:
 Send mail to:
    mail-server@rtfm.mit.edu 

 Containing the following in the body of the message:
    send usenet/news.answers/mail/filtering-faq

UUCP:
 uunet!/archive/usenet/news.answers/mail/filtering-faq

Hard Copy:
 A printed version of this FAQ is in Chapter 25 of the book 
 "Internet Secrets" by John R. Levine and Carol Baroudi; published 
 1995 by IDG Books; ISBN 1-56884-452-2.