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Sendmail, 3rd Edition by Bryan Costales

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The access Database

The access database was introduced in V8.9 sendmail, and improved upon in V8.10. It provides a single, central database with rules to accept, reject, and discard messages based on the sender name, address, or IP number. It is enabled with the access_db configuration feature.[17]

For example, consider an access database with the following contents:

From:postmaster@spam.com   OK
From:spam.com              REJECT

Here, mail from postmaster at the site spam.com is accepted, while mail from any other sender at that site is rejected.

Note that this example uses V8.10 syntax. Next we will describe the access database using the old V8.9 syntax, then describe the V8.10 and V8.12 updates.

Enabling the access Database Generally

To enable use of this access database, declare it in your mc configuration file like this:

FEATURE(`access_db')

This enables use of the access database, and enables the default database type and path as:

hash /etc/mail/access          V8.11 and earlier
hash -T<TMPF> /etc/mail/access V8.12 and above

Note that with V8.12 and above a -T<TMPF> has been added to specify that temporary errors should return a 4xy SMTP code.

If you wish to use a different database type or pathname, you can do so by providing an appropriate argument to the access_db feature:

FEATURE(`access_db', `hash -o /etc/mail/access')        V8.11 and earlier
FEATURE(`access_db', `hash -o -T<TMPF> /etc/mail/access') V8.12 and above

Here, we add the -o switch (-o) to the definition to make the existence of the /etc/mail/access ...

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