Quickie Mail Server Setup Tutorial using Sendmail, Dovecot, SquirrelMail, SpamAssassin on Fedora 8 (Part I)

Note: Make sure to check the conventions I use before going through the tutorial.

Hullo world! For this post, we'll setup a quickie mail server. The idea here as with most other post, is to setup basic mail server to get you going, so you can spend your time fiddling with advance setting rather than groping your way on how setup mail server. Note that a critical component (that we won't tackle here) is a working DNS setup. It's crucial that you have an MX record pointing to working domain. If you haven't setup one up yet, check this quickie post. Otherwise, you need to set one up before proceeding.

Also, we'll use the "exampledns.com" previously setup as example domain. Hostname of the machine that you working on is "node1.exampledns.com". You also have local user 'gene' and 'user1'

For this series of post, we'll setup the following:
- Sendmail
- Dovecot
- SquirrelMail
- SpamAssassin

Basic Setup of Sendmail:

Step 1: Log in as root and install all the necessary packages:

# yum -y install M4 sendmail sendmail-cf sendmail-doc dovecot

Step 2: By default, Sendmail only accept connection from loopback device or 127.0.0.1, you need to enable Sendmail to accept connection to your other network interface. To do this, edit /etc/mail/sendmail.mc (make sure to create a backup first), look for the following entry,

DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl

And change it to,

dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl

Step 3: Edit /etc/mail/local-host-names and list all hostnames in your network that is acting as MX recipient. In my case, I have the following:

exampledns.com
node1.exampledns.com
mail.exampledns.com

Note that you might have a different settings here.

Step 4: Update the sendmail.cf config file and restart Sendmail service and then send test mail.

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

# service sendmail restart
# su - gene
[gene]$ echo | mail -s "test email from gene" user1@exampledns.com
[gene]$ su - user1
[user1]$ mail

Note: From local user gene, you should be able to see emails from root account.

Step 5a: By default, Sendmail doesn't use 'write' your domain name to outgoing email. The above email from gene would show on user1 as coming from gene@localhost.localdomain. To write the '@exampledns.com' domain to outgoing emails, edit /etc/mail/sendmail.mc and find the following settings:

dnl MASQUERADE_AS(`domain-name.com')dnl
dnl FEATURE(masquerade_entire_domain)dnl
dnl FEATURE(masquerade_envelope)dnl

Step 5b: Remove the prefix dnl, so you have something similar below. And specify the domain name you wish that your outgoing emails will use. Edit /etc/mail/sendmail.mc and add the following settings:

MASQUERADE_AS(`exampledns.com')dnl
FEATURE(masquerade_entire_domain)dnl
FEATURE(masquerade_envelope)dnl

Step 5c: Update sendmail config file and restart your Sendmail service

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

# service sendmail restart

Your outgoing mail should now look like gene@exampledns.com.

Miscellaneous Setup of Sendmail:

Step 6a: Set-up your aliases. For example, all inquiries sent to inquiry@exampledns.com will be forwarded to gene@exampledns.com. Edit /etc/aliases file and add the following entry at the bottom of the file:

inquiry: gene@exampledns.com

Note: To refer to a filename for a list of user that will resolve to an alias (ie. mailing list setup), use the following format:

alias: :include:/path/to/file

So you could have something like:

company-announcement: :include:/etc/mail/staff-list

Step 6b: Restart Sendmail:

# service sendmail restart
or
# newaliases

Step 7a: To accept or reject mails coming from selected users or domain, edit the /etc/mail/access file and add something along the lines of:

spammer@spam.com REJECT

192.168.3.200 DISCARD

sendmail.com REJECT

(RELAY reject the sender or recipient with general purpose error message. DISCARD drop the mail without any error message or notification to the sender or recipient.)

Step 7b: Rebuild the access file database and restart the Sendmail program:

# makemap hash /etc/mail/access.db < /etc/mail/access

# service sendmail restart

Step 8a: Set a cap the size of email attachment. Add the following entries to sendmail.mc

define(`confMAX_MESSAGE_SIZE', `size-in-bytes')dnl

Step 8b: Update sendmail config file and restart your Sendmail service

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

# service sendmail restart

Step 9: Setup your imap server using Dovecot. Log in as root, edit /etc/dovecot.conf and add the following:

# cp /etc/dovecot.conf /etc/dovecot.conf-original
# vi /etc/dovecot.conf

protocols = imap pop3

# service dovecot start

Note: In future post, we'll setup a more secure IMAP server using certificates.

Step 10: Test your imap server using your email client (ie. kmail, thunderbird, evolution, etc)

Watch out for the continuation of this Quickie Mail Server Setup Tutorial using Sendmail, Dovecot, SquirrelMail, SpamAssassin on Fedora 8.