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

NOTE: Because /etc/mail/access is a database, after creating the text file, you
must use the following makemap command to create the database map.
makemap dbm /etc/mail/access < /etc/mail/access
For more information on the makemap utility, type man 1M makemap at the HP-UX
prompt.
Relay local from
This option allow Sendmail to relay mail messages when the sender of the mail message
is a valid user on that machine. Consider a valid user abc on host 1. A user cbz on
host 2 can connect to host 1 as user abc and send mail to another user xyz on host 3.
This means that host 1 is now acting as a local relay agent.
You must enable this option only if absolutely necessary because it opens a window
for spammers. Specifically, spammers can send mail to your mail server that claims to
be from your domain (either directly or through a routed address), and you can then
go ahead and relay it out to arbitrary hosts on the Internet.
Blacklist recipients
This feature enables Sendmail to block incoming mail messages destined to certain
recipient user names, host names, or addresses. This feature also restricts you from
sending mail messages to addresses with an error message or REJECT value in the
access database file. For example, if you have the following entries in the access database
file:
badlocaluser 550 Mailbox disabled for this username
host.mydomain.com 550 That host does not accept mail
user@otherhost.mydomain.com 550 Mailbox disabled for this recipient
These entries prevent a recipient of badlocaluser@mydomain.com, any user at
host.mydomain.com, and the single address user@otherhost.mydomain.com
from receiving mail.
spammer@aol.com REJECT
cyberspammer.com REJECT
The entries in the access db file indicate that Sendmail cannot send mail messages to
spammer@aol.com or to the domain cyberspammer.com.
Accept unresolvable domains
Setting this option, allows Sendmail to accept all those MAIL FROM: parameters that
are not fully qualified, that is, if the host portion of the argument to MAIL FROM:
command cannot be located in the host name service (for example, DNS).
56 Configuring and Administering Sendmail