1. Mail Server Three major components MTA MUA MDA Mail Transfer Agent
sendmail, Postfix, Dovecot
MUA
Mail User Agent
mail, Evolution
MDA
Mail Delivery Agent
procmail, maildrop

2. E-mail systems are heavily dependant on name resolution.
For small networks you could use /etc/hosts, but any mail system that requires Internet access needs access to a fully functional DNS server

3. MTA’s sendmail and Postfix Dovecot
Use SMTP to send mail
Dovecot
is used to enable POP3 and/or IMAP to receive mail.
SMTP, POP3 and IMAP are protocols, a set of rules for transferring data used by various mail transfer agents.

4. Reception with Dovecot
Add the appropriate directive in the Dovecot configuration file.
Make sure Dovecot is set to start at boot
POP current version POP3
Centralized mail depository, clients download messages for processing at the local host
IMAP current version IMAP4
Maintains all messages on the server

5. Dovecot Configuration File http://wiki.dovecot.org/QuickConfiguration
/etc/dovecot.conf
protocols = pop3 pop3s imap imaps
listen = :10100
#ssl listen = :10943
For POP3S and IMAPS support
#ssl_disable = no
Activating Dovecot
chkconfig dovecot on
service dovecot start

6. sendmail Configuration http://www.sendmail.org/
Configured by two directory of files
/etc/mail
/usr/share/sendmail-cf
Two basic configuration files
sendmail-cf
for incoming mail
submit-cf
for outgoing mail

7. sendmail.cf sendmail.mc access domaintable mail configuration file
a macro that is easier to edit, used to generate a new sendmail.cf file
access
supports access control to your sendmail server, default is for local computer, host name or networks can be added to the list with a message to REJECT, DISCARD, or RELAY
domaintable
map different domains
i.e. what.com who.com
would forward mail sent to to

8. statistic submit.cf sumbit.mc virusertable
Collects statistics on sendmail, can be read with the mailstats command
submit.cf
The main outgoing sendmail configuration file
sumbit.mc
a macro that is easier to edit, used to generate a new submit.cf file
virusertable
Supports forwarding for users outside of your network

9. Basic Directives in sendmail.mc
DAEMON_OPTIONS(`Port=smtp,Addr= , Name=MTA')dnl
FEATURE(`accept_unresolvable_domains')dnl
Allow remote computers or network access to the local sendmail server you need to add their names or address to the access file.
connect: RELAY

10. make –C /etc/mail
command is used to generate new .cf files from .mc files that have been edited.
Also processes files like access and virtusertable to database files (*.db) for use by sendmail