If you ever have to approach sendmail, then this is *the*
book. It covers all the possible options, files and
switches in full, and includes details on the new m4
files and option typed in v8 sendmail.

The introduction and beginners guide has perhaps a little
too steep a learning curve for beginners but is acceptable
for those with a vague knowledge of SMTP and a familiarity
with your OS.

Anybody who needs to use sendmail should acquire a copy
of 'the Bat Book', at least for reference.