The source-tree is also available thru Anonymous CVS, and Anonymous RSYNC.
Info about the email-list about ZMailer is there.
Some of the documents of the ZMailer have been HTMLized, and are available at following links:
The original author of the ZMailer is Rayan Zachariassen (hence the ``Z'' at the name) who was at University of Toronto back in late 1980es, and didn't like the way the sendmail was able to cause serious system loads when doing deliveries, nor the way how it appeared to find a new security hole at the sendmail nearly every week... (That was back n 1980es with sendmail-5.x.)
The current author, and keeper of ZMailer is Matti Aarnio, who has been doing things of his interests to the ZMailer since 1990, and has been sole keeper of mailer since 1992, when Rayan went to private sector, and disappeared from academic community.
Matti Aarnio's email address is email@example.com, and another at firstname.lastname@example.org