HP-UX Mailing Services Administrator's Guide (B2355-91064)

Relay based on MX
Setting this option, will turn ON the ability to allow relaying based on the MX records
of the host portion of an incoming recipient; that is, if an MX record for host foo.com
points to your site, you will accept and relay mail addressed to foo.com.
Relay hosts only
This option changes the behavior of the access database and class R macro to lookup
individual host names only. By default, names that are listed as RELAY in the access
database file and the class R ($=R) macro are domain names, and not host names.
Access db
The access database (db) is a user-defined file to decide the domains from which you
want to receive or reject mail messages. The entries in the access db file are either
domain names, IP addresses, hosts names, or e-mail addresses. Every line of the access
db file has a key and a value pair.
The key can be an IP address, a domain name, a hostname, or an e-mail address. The
value part of the database can contain the following values:
OK
Accepts mail even if other rules in the running ruleset reject it. For
example, if the domain name is unresolvable.
RELAY
Accepts mail addressed to the indicated domain or received from
the indicated domain for relaying through your SMTP server.
RELAY also serves as an implicit OK for the other checks.
REJECT
Rejects the sender or recipient with a general purpose message.
DISCARD Discards the message completely using the $#discard mailer.
This value works only for sender addresses (that is, it indicates
that you must discard anything received from the indicated
domain).
### any text ### specifies an RFC 821-compliant error code and any text
specifies is a message to return for the command.
The default access db file is /etc/mail/access. You have to make a direct
modification to /etc/mail/sendmail.cf if you want to use a non-standard access
database filename.
Modifying the Default Sendmail Configuration File 55