Whoa! I hadn’t realized that I have in my archives mail configuration files from no later that 1993.  Here is one rewrite file from “research”, as in “research!dmr":

more rewrite 

# local mail

[^!@%.=]+               translate       "exec /v/lib/upas/translate '&'"

local!([^!@]+)          >>              /usr/spool/mail/\1

\l!(.+)                 alias           \1

research\.att\.com!(.+) alias           \1

research\.research\.att\.com!(.+)       alias           \1

plan9\.research\.att\.com!(.+)  alias   \1

league\.att\.com!(.+)   alias           league!\1

league\.research\.att\.com!(.+) alias   league!\1

league!(.+)             alias   \1

# convert @ format to ! format

([^!]+)@([^!@]+)        alias   \2!\1

# convert % addresses for us only.

([^!]+)%([^!%]+)        alias   \2!\1

# network gateways

uucp!(.+)               alias   \1

bitnet!(.+)             alias   inet!bitnet!\1

uunet!(.+)              alias   inet!uunet.uu.net!\1

.*tempo\.att\.com!.*    | "exec /v/lib/upas/route '\s' allegra.att.com" "'&'"

vax135!(.*)             | "exec /v/lib/upas/route '\s' big.l1135.att.com" "\1"

\[([^!]+)\]!(.+)        |       "exec /v/lib/upas/route.ip '\s' '\1'" "'\2'"

([^!]+\.att\.com)!(.+)  |       "exec /v/lib/upas/route '\s' '\1'" "'\2'"

[^!]+\..*               |       "exec /v/lib/upas/route '\s' inet" "'&'"

([^!]+)!(.+)            |       "exec /v/lib/upas/route '\s' '\1'" "'\2’"

====

and here is the rewrite file for the mail application gateway no later than 1998:

#  get rid of the .att.com domain part of the name.

#  It's not used internally.

([^%!@.]+)\.att\.com!(.+) alias \1!\2

# the following must change: we don't really want these used.

att\.com!(.+) alias \1

att\.arpa!(.+) alias \1

(arpa|att-gw|gate)(\.arpa)?!(.+) alias \3

# rerouting:

uunet!(.+) alias uunet.uu.net!\1

mcvax!(.+) alias uunet.uu.net!mcvax!\1

local!(.+) >> /usr/spool/mail/\1

#tempo!(.+) alias research!tempo!\1

sola!(.+) alias jones!\1

# a very common mistake

.*! | "echo Bad address: '&'; exit 1"

# a problem at cunyvm.

cunyvm\.cuny\.edu!(cunyvm\.cuny\.edu)!(.+) alias \1!\2

# gateways

uucp!(.+) alias \1

csnet!(.+) alias relay.cs.net!\1

bitnet!([^!]+)!(.+) alias CUNYVM.CUNY.EDU!\1.BITNET!\2

bitnet!([^!]+)@([^!]+) alias CUNYVM.CUNY.EDU!\2.BITNET!\1

mailnet!([^!]+)!(.+) alias mit-multics.arpa!\1.MAILNET!\2

acsnet!(.+) alias research!&

attmail!(.+) auth false

# attmail!(.+) alias attbl!attmail!\1

# convert @ format to ! format always (so locals can use @ format)

(.+)@([^!@]+) alias \2!_pct_!\1

# convert % format only if the first hop isn't on the internet.

([^!]+)%([^!%]+) alias \2!\1

([^!.]+)!(.+!)?_pct_!(.+)%([^!%]+) alias \1!\2\4!_pct_!\3

([^!.]+)!(.+)%([^!%]+) alias \1!\3!_pct_!\2

# get rid of our _pct_ tag

((.+)!)?_pct_!(.+) alias \1\3

# don't route through research just to get to another machine

# this MUST follow the %@ conversion

research!([^!]+)!(.+) alias   \1!\2

research!([^!]+) alias inet!\1

# at this point, anything without a "."  in the first component

inet!(.+)               |       "exec /usr/lib/upas/route.inet '\s' inet" "'\1'"

(att|coma|alice|allegra)!(.+) |       "exec /usr/lib/upas/route.toatt '\s' \1" "'\2'"

([^.!]+)!(.+)           |       "exec /usr/lib/upas/route.toatt '\s' att" "'&'"

# Only local or Internet Domain addresses below this line.

# various semi-official domain addresses

([^!]+)\.(csnet|bitnet|acsnet|mailnet|uucp)!(.*) alias \2!\1!\3

# Domain routings - arranged with the other AT&T postmasters

sf\.att\.com!(.+) alias attunix!\1

([^!.]+)\.sf\.att\.com!(.+) alias attunix!\1!\2

([^!.]+)\.(astro|mercury|phone|div111)\.nj\.att\.com!(.+) alias   \1!\2

([^!]*\.)?mis\.oh\.att\.com!.+ alias att!&

([^!]*\.)?dptg\.att\.com!.+ alias dptg!&

([^!]*\.)?garage(\.nj)?\.att\.com!.+ alias garage!&

([^!]*)\.tempo(\.nj)?\.att\.com!(.+) alias \1!\3

([^!]*\.)?homer\.nj\.att\.com!.+ alias ulysses!&

([^!]+)\.aloft\.att\.com!(.+) alias aloft!&

(([^!]*\.)?uso\.att\.com)!(.+)  |  "smtpqer -n -d .att.com -H att.att.com '\s' '\1'" "'\3'"

([^!]+)\.att\.com(\.)?!(.+) | "echo 'Unknown AT\&T domain:' '&' >\&2; exit 1"

# Ready to send Internet mail.

([^!]+)!(.+)            |  "smtpqer -n -d .att.com -H att.att.com '\s' '\1'" "'\2'"

# carefully selected local translates

postmaster alias coma!postmaster

[^!@%]*[._]+[^!@%]* translate \

"exec /usr/lib/post/post -o '%^25name  %20ema  %^city, %+state ' -x -- '&'"

[^!@%]+ translate "exec translate '&'"

[^!@%]+ >> /usr/spool/mail/&