.forward	yes (empty files; can enable/disable mail to /file or |command)
/usr/mail	yes (compile time option)
/usr/spool/mail	yes (compile time option)
/var/mail	yes (compile time option)
/var/spool/mail	yes (compile time option)
:include:	yes (mail to /file and |command is off by default)
address probing	yes (optional persistent database)
aliases		yes (can enable/disable mail to /file or |command)
bare newlines	yes (but will send CRLF)
blacklisting	yes (client name/addr; helo hostname; mail from; rcpt to)
connection caching yes (SMTP shared cache; LMTP shared cache)
content filter	yes (before and after queue, internal and external)
db tables	yes (compile time option)
dbm tables	yes (compile time option)
delivered-to	yes (configurable with prepend_delivered_header)
dsn		yes
enhanced status codes	yes
errors-to:	no (removed with Postfix 2.2)
esmtp		yes
etrn support	yes (per-destination log for authorized destinations only)
fcntl locking	yes (runtime configurable)
flock locking	yes (runtime configurable)
genericstable	yes (Postfix 2.2 generic(5) table)
greylist	yes (delegated policy script)
home mailbox	yes
ident lookup	no
ipv6	        yes (compatibility for ipv4-only systems)
ldap tables	yes (contributed)
lmtp support	yes (client only)
luser relay	yes
m4 config	no
mail to command	yes (configurable for .forward, aliases, :include:)
mail to file	yes (configurable for .forward, aliases, :include:)
maildir		yes (in home, system mailspool, /file/name/ alias)
mailertable	yes (it's called transport)
mailq		yes
majordomo	                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 