Linux Server Security, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Mail Delivery Agents

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1. Set check_recipient_access = hash:/etc/postfix/access.

2. Specify a relaying policy with

smtp_recipient_restrictions, e.g.:

smtpd_recipient restrictions =

permit_mynetworks

hash:/etc/postfix/access

reject_unauth_destination

3. Create /etc/postfix/access (check the access(5) manpage for format/syntax).

4. Run

postmap hash:/etc/postfix/access to convert the file into a database.

Repeat this step after each time you edit /etc/postfix/access.

smtpd_client_restrictions

Use this parameter to block mail from specific senders or originating domains.

Senders to block may be named both specifically, via an external map file such

as the access database, and generally, via values such as the following:

reject_maps_rbl

Enables use of the Real Time Blackhole List described in the “Sendmail” sec-

tion of this chapter; this requires

maps_rbl_domains to be set

reject_unknown_client

Rejects mail from clients whose hostname can’t be determined

See the file /etc/postfix/sample-smtpd.cf for a full list of valid

smtpd_client_

restrictions

settings.

maps_rbl_domains

Specifies one or more Blackhole database providers—e.g., blackholes.mail-abuse.

org.

Mail Delivery Agents

As important as it is to run secure Mail Transfer Agent services, it’s only part of your

email picture, and it isn’t even ...