Section 19.1.5	Prior to V8.10, any rules that appeared before the first `S` command were added to rule set 0 by default. With V8.10 and later, sendmail rejects any rules that are not preceded with a valid rule set definition.
Section 19.3	Rule set 3 has also become known as the canonify rule set (V8.10 and later).
Section 19.3.3	Prior to V8.10, sendmail was able to handle addresses that are in route address syntax. Beginning with V8.10, sendmail removes route addresses by default.
Section 19.4	Rule set 4 has also become known as the final rule set (V8.10 and later).
Section 19.5	Rule set 0 has also become known as the parse rule set (V8.10 and later).
Section 19.6.1	Rule set 5 has also become known as the localaddr rule set, and new rules can be added to it with the `Local_localaddr` rule set (V8.10 and later).
Section 19.9	Several new rule sets have been introduced that are designed to check and reject envelope information and header contents, and to make general policy decisions. All the new rule sets are listed in Table B-1.
srv_features	The `srv_features` rule set allows or disallows selected features based on connection information, such as STARTTLS, AUTH, and PIPELINING (V8.12 and later).

Table B-1. New rule sets
Rule set	Version	Description
`check_compat`	V8.8 and later	Checks just before delivery
`check_data`	V8.12 and later	Checks just after DATA
`check_eoh`	V8.10 and later	Validates after headers are read
`check_etrn`	V8.10 and later	Allows or disallows ETRN
`check_expn`	V8.10 and later	Allows or disallows EXPN
`check_mail`	V8.8 and later	Checks the envelope-sender address
`check_rcpt`	V8.8 and later	Checks the envelope-recipient address
`check_relay`	V8.8 and later	Checks incoming network connections
`check_vrfy`	V8.10 and later	Allows or disallows SMTP VRFY