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Chapter 15. Email

For example, if you want all email addressed to any

domain.com

account to be delivered to

<

bob@otherdomain.com

>, you need to add a line similar to the one below to the

virtusertable

file:

@domain.com

bob@otherdomain.com

Then, to add this new information to the

virtusertable.db

file, execute

makemap hash

/etc/mail/virtusertable

/etc/mail/virtusertable

as root. This will create a new

virtusertable.db

containing the new configuration.

15.3.4. Common Sendmail Configuration Changes

Although a default

sendmail.cf

file is installed in

/etc/mail/

during the Red Hat Linux installa 

tion process, you will need to alter it to use some of the program's more advanced features.

When altering the Sendmail configuration file, it is best generate a entirely new

/etc/mail/sendmail.cf

file instead of editing an existing one.

Caution

Before changing the sendmail.cf file, it is a good idea to backup the default version.

To add the desired functionality Sendmail edit the

/etc/mail/sendmail.mc

file. When you

are finished, use the

m4

macro processor to generate a new

sendmail.cf

by executing the

m4

/etc/mail/sendmail.mc

/etc/mail/sendmail.cf

command. After creating a new

/etc/mail/sendmail.cf

, you must restart Sendmail to make it take effect. The easiest way to do

this is to type the

/sbin/service sendmail restart

command as root.

By default, the

m4

macro processor is installed with Sendmail and is part of the

sendmail cf

pack 

age.

Important

The default sendmail.cf does not allow sendmail to accept network connections from any host

other than the local computer. If you want to configure sendmail as a server for other clients, please

edit /etc/mail/sendmail.mc and change DAEMON_OPTIONS to also listen on network devices or

comment out this option all together. Then regenerate /etc/mail/sendmail.cf by running:

m4 /etc/mail/sendmail.mc

/etc/mail/sendmail.cf

This configuration should work for most SMTP only sites. It will not work for UUCP (UNIX to UNIX

Copy) sites; you will need to generate a new

sendmail.cf

if you must use UUCP mail transfers.

You should consult the

/usr/share/sendmail cf/README

file before you edit any of the files

in the directories under the

/usr/share/sendmail cf

directory, as they can affect how future

/etc/mail/sendmail.cf

files are configured.

15.3.4.1. Masquerading

One common Sendmail configuration is to have a single machine act as a mail gateway for all

the machines on the network. For instance, a company may want to have a machine called

mail.bigcorp.com

that handles all their email and assigns a consistant return address to all out

going mail.