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Re: Running a POP3 / SMTP server


I have appended my notes on how to do this for 7.3. I've cut and pasted it
from a word doc file, so I hope the formatting does not mess up. If you spot
any mistakes please let me know.

If you are doing anything with sendmail, you really should also have a copy
of the sendmail BAT book.

Good Luck

----- Original Message -----
From: "Don Hirlinger" <tunadog tunadog com>
To: "Valhala List" <valhalla-list redhat com>
Sent: Saturday, January 04, 2003 1:00 AM
Subject: Running a POP3 / SMTP server

> Hi folks,
> I would like to run a POP3/SMTP server on my Linux 7.3 .
> What do I need to do?
> Any help would be appreciated.
> Don


Standard install from RH 7.3 CD uses Sendmail Version 8.11.6

Sendmail is installed as standard on server installations. For security
reasons it is set to only allow incoming email from the local machine
(localhost) and it does not provide mechanisms to get email (ie POP3 or IMAP

To configure email to work as a server you must :

·         Reconfigure sendmail

·         Edit several configuration files

·         Restart sendmail

·         Install an email access product - (we use ipop3d)

·         Configure the email access product to work correctly and securely

·         Finally you can add user accounts

Additional desireable activities are also required

·         Monitoring tools to report on performance and activities

·         Spam & Virus filtering tools to minimise damage to customers

·         Log management tools to ensure logs are correct & consistent

·         Log management tools to purge and anonymise logs so that they are
compliant with privacy legislation

Edit Sendmail config file

When people first install sendmail, the first cry for help is "why doesn't
it work". In most cases the reason it does not work is because one of the
settings in the sendmail master configuration file has set it up, so that
the server will only receive incoming email (using SMTP port 25 service)
from the machine that sendmail is installed on.

Comment out line in /etc/mail/sendmail.mc :

dnl DAEMON_OPTIONS("Port=smtp,Addr=, Name=MTA')

Rebuild sendmail.cf and restart sendmail:

m4 /etc/mail/sendmail.mc > /etc/sendmail.cf

/sbin/service sendmail restart

This allows sendmail to receive email from other machines.

Edit configuration files :

Access - This file describes the hosts/sub nets that are allowed to RELAY in
or be REJECTED. Think of this as an enemies and friends file. A friend who
uses another ISP for access may wish to use our email services, in which
case we say allow it. This happens with ADSL users a lot.

abbtel.com           RELAY

abbtel.co.uk  RELAY

abbtel.org           RELAY

spammer.net          DENY

user badisp org      DENY

Similiarly you can elect to refuse entire domains and ip subclasses or
individual host machines. So this is a useful file.  The sendmail.cf file
describes this file as the "Spam Stomper". In the above example all email
from abbtel is allowed (and is allowed to RELAY from other ISPs as well).
All email from the domain spammer.net & the user badisp org is rejected.

Mailtertable - This file overrides domains

Local-host-names - All the different alias names for this machine.  The
AbbTel addresses can come in using one of 4 domain names, abbtel.co.uk,
abbtel.com, abbtel.org, or abbtel.org.uk. In order for AbbTel staff to
receive email using all 4 forms, the local-host-names file contains  :








Virtusertable - Maps incoming users, using the domain name. This file can be
a pain when users have multiple domain names that all need to behave in the
same way :

tim abbtel com       timsaccount

support abbtel com   support

* abbtel com  admin

tim abbtel co uk     timsaccount

support abbtel co uk support

* abbtel com uk      admin

Restart the service

Once all configuration files are correctly configured, all the necessary
build operations

cd /etc/mail


/sbin/service sendmail restart

To test if sendmail is running correctly, test that the SMTP service is
working, first locally then from a remote machine. You do this with telnet &
the port used by the SMTP protocol - port 25.

telnet localhost 25

You should enter a few test sequences to check everything is working ok.

mail from: testing yourdomain com

rcpt to:  username


Test data

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