Mail Transport Agents
~]# alternatives --config mta
chkconfig service_name on | off
1. Postfix
1.1. The Default Postfix Installation
/usr/sbin/postfix
.
This daemon launches all related processes needed to handle mail delivery./etc/postfix/
directory.
The following is a list of the more commonly used files:-
access
— Used for access control, this file specifies which hosts are allowed to connect to Postfix. -
main.cf
— The global Postfix configuration file. The majority of configuration options are specified in this file. -
master.cf
— Specifies how Postfix interacts with various processes to accomplish mail delivery. -
transport
— Maps email addresses to relay hosts.
aliases
file
can be found in the /etc/
directory.
This file is shared between Postfix and Sendmail. It is a configurable list required by the mail protocol that describes user ID aliases.Configuring Postfix as a server for other clients
/etc/postfix/main.cf
file
does not allow Postfix to accept network connections from a host other than the local computer. For instructions on configuring Postfix as a server for other clients, see Section 19.3.1.2,
“Basic Postfix Configuration”.postfix
service
after changing any options in the configuration files under the /etc/postfix
directory
in order for those changes to take effect:
~]# service postfix restart
1.2. Basic Postfix Configuration
root
to
enable mail delivery for other hosts on the network:-
Edit the
/etc/postfix/main.cf
file with a text editor, such asvi
. -
Uncomment the
mydomain
line by removing the hash sign (#
), and replace domain.tld with the domain the mail server is servicing, such asexample.com
. -
Uncomment the
myorigin = $mydomain
line. -
Uncomment the
myhostname
line, and replace host.domain.tld with the host name for the machine. -
Uncomment the
mydestination = $myhostname, localhost.$mydomain
line. -
Uncomment the
mynetworks
line, and replace 168.100.189.0/28 with a valid network setting for hosts that can connect to the server. -
Uncomment the
inet_interfaces = all
line. -
Comment the
inet_interfaces = localhost
line. -
Restart the
postfix
service.
/etc/postfix/main.cf
configuration
file. Additional resources including information about Postfix configuration, SpamAssassin integration, or detailed descriptions of the /etc/postfix/main.cf
parameters
are available online at http://www.postfix.org/.1.2.1. Configuring Postfix to Use Transport Layer Security
Important
SSL
,
if it is enabled, and using only TLSv1.1
or TLSv1.2
.
Backwards compatibility can be achieved using TLSv1.0
.
Many products Red Hat supports have the ability to use SSLv2
or SSLv3
protocols.
However, the use of SSLv2
or SSLv3
is
now strongly recommended against.1.3. Using Postfix with LDAP
LDAP
directory
as a source for various lookup tables (e.g.: aliases
, virtual
, canonical
,
etc.). This allows LDAP
to
store hierarchical user information and Postfix to only be given the result of LDAP
queries
when needed. By not storing this information locally, administrators can easily maintain it.1.3.1. The /etc/aliases lookup example
LDAP
to
look up the /etc/aliases
file.
Make sure your /etc/postfix/main.cf
file
contains the following:alias_maps = hash:/etc/aliases, ldap:/etc/postfix/ldap-aliases.cf
/etc/postfix/ldap-aliases.cf
file
if you do not have one already and make sure it contains the following:server_host = ldap.example.com
search_base = dc=example, dc=com
ldap.example.com
, example
,
and com
are
parameters that need to be replaced with specification of an existing available LDAP
server.The /etc/postfix/ldap-aliases.cf file
/etc/postfix/ldap-aliases.cf
file
can specify various parameters, including parameters that enable LDAP
SSL
and STARTTLS
.
For more information, see the ldap_table(5)
man
page.LDAP
,
see Section 20.1,
“OpenLDAP”.