gistfile1.txt

$ host -t mx yale.edu
yale.edu mail is handled by 9 vm-emlprdimg-06.its.yale.edu.
yale.edu mail is handled by 9 vm-emlprdimg-07.its.yale.edu.
yale.edu mail is handled by 9 vm-emlprdimg-03.its.yale.edu.
yale.edu mail is handled by 9 vm-emlprdimg-04.its.yale.edu.
yale.edu mail is handled by 9 vm-emlprdimg-05.its.yale.edu.

$ host -t mx connect.yale.edu
connect.yale.edu mail is handled by 10 x10-caht4.its.yale.edu.
connect.yale.edu mail is handled by 20 mr1.its.yale.edu.
connect.yale.edu mail is handled by 20 mr2.its.yale.edu.
connect.yale.edu mail is handled by 20 mr3.its.yale.edu.
connect.yale.edu mail is handled by 20 mr4.its.yale.edu.
connect.yale.edu mail is handled by 20 mr5.its.yale.edu.
connect.yale.edu mail is handled by 20 mr6.its.yale.edu.
connect.yale.edu mail is handled by 10 x10-caht1.its.yale.edu.
connect.yale.edu mail is handled by 10 x10-caht2.its.yale.edu.
connect.yale.edu mail is handled by 10 x10-caht3.its.yale.edu.

$ host -t mx yale.net
yale.net mail is handled by 9 vm-emlprdimg-04.its.yale.edu.
yale.net mail is handled by 9 vm-emlprdimg-05.its.yale.edu.
yale.net mail is handled by 9 vm-emlprdimg-06.its.yale.edu.
yale.net mail is handled by 9 vm-emlprdimg-07.its.yale.edu.
yale.net mail is handled by 9 vm-emlprdimg-03.its.yale.edu.

$ host -t mx connect.yale.net
connect.yale.net mail is handled by 20 mr2.its.yale.edu.
connect.yale.net mail is handled by 20 mr3.its.yale.edu.
connect.yale.net mail is handled by 20 mr4.its.yale.edu.
connect.yale.net mail is handled by 20 mr5.its.yale.edu.
connect.yale.net mail is handled by 20 mr6.its.yale.edu.
connect.yale.net mail is handled by 10 lab-ex10cas1.yu.yale.net.
connect.yale.net mail is handled by 10 lab-ex10cas2.yu.yale.net.
connect.yale.net mail is handled by 20 mr1.its.yale.edu.



http://www.sendmail.com/sm/open_source/docs/m4/features.html
old+*@foo.org	new+%[email protected]
gen+*@foo.org	%[email protected]
+*@foo.org	%1%[email protected]
[email protected]	Z%[email protected]
@bar.org	%1%3

and other forms are possible.

Note: to preserve "+detail" for a default case (@domain) %1%3 must be used as RHS. There are two wildcards after "+": "+" matches only a non-empty detail, "*" matches also empty details, e.g., [email protected] matches +*@foo.org but not [email protected]. This can be used to ensure that the parameters %2 and %3 are not empty.

All the host names on the left hand side (foo.com, bar.com, and baz.org) must be in class {w} or class {VirtHost}. The latter can be defined by the macros VIRTUSER_DOMAIN or VIRTUSER_DOMAIN_FILE (analogously to MASQUERADE_DOMAIN and MASQUERADE_DOMAIN_FILE). If VIRTUSER_DOMAIN or VIRTUSER_DOMAIN_FILE is used, then the entries of class {VirtHost} are added to class {R}, i.e., relaying is allowed to (and from) those domains. The default map definition is:
hash /etc/mail/virtusertable

A new definition can be specified as the second argument of the FEATURE macro, such as
FEATURE(`virtusertable', `dbm /etc/mail/virtusers') 

@yale.net  %1%[email protected]
[email protected] [email protected]