Sendmail, 3rd Edition

Chapter 20

discard	The discard delivery agent accepts then discards email messages (V8.9 and later).
/= (forward slash)	The /= delivery-agent equate defines a chroot(8) directory (V8.10 and later).
See this section	Delivery can now be made to Unix domain sockets (V8.10 and later).
See this section	It is now possible to delete from, add to, and modify delivery-agent flags using the MODIFY_MAILER_FLAGS mc command (V8.10 and later).
m=	The m= delivery-agent equate limits the number of envelopes that can be delivered during any single SMTP or LMTP connection (V8.10 and later).
P=	P=[TCP] is fully deprecated as of V8.10, and disallowed as of V8.12.
Q=	The Q= delivery-agent equate specifies which queue group to use (V8.12 and later).
r=	The r= delivery-agent equate limits the number of recipients allowed per envelope (V8.12 and later).
W=	The W= delivery-agent equate sets the timeout for a delivery agent to complete delivery (V8.10 and later).
F=%	The F=% delivery-agent flag specifies that delivery should be held until an ETRN command or a -q[IRS] run (V8.10 and later).
F=1 (one)	The F=1 delivery-agent flag specifies that null bytes should be removed from headers (V8.10 and later).
F=2	The F=2 delivery-agent flag forces SMTP even if ESMTP is offered (V8.12 and later).
F=6	The F=6 delivery-agent flag requires the high bit to always be stripped from headers (V8.10 and later).
F=z	The F=z delivery-agent flag requires delivery to use the LMTP protocol ...