rewrite

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

# case conversion for postmaster
pOsTmAsTeR	alias		postmaster

# local mail
[^!@]+		translate	"/bin/upas/aliasmail '&'"
local!(.*)	>>		/mail/box/\1/mbox
\l!(.*)		alias		\1
(helix|helix.bell-labs.com)!(.*)	alias		\2

# we can be just as complicated as BSD sendmail...
# convert source domain address to a chain a@b@c@d...
@([^@!,]*):([^!@]*)@([^!]*)	alias	\2@\3@\1
@([^@!]*),([^!@,]*):([^!@]*)@([^!]*)	alias	@\1:\3@\4@\2

# convert a chain a@b@c@d... to ...d!c!b!a
([^@]+)@([^@]+)@(.+)	alias	\2!\1@\3
([^@]+)@([^@]+)		alias	\2!\1

# /mail/lib/remotemail will take care of gating to systems we don't know
([^!]*)!(.*) 		| 		"/mail/lib/qmail '\s' 'net!\1'" "'\2'"