Mail Server

• Three major components• MTA

– Mail Transfer Agent• sendmail, Postfix, Dovecot

• MUA– Mail User Agent

• mail, Evolution

• MDA– Mail Delivery Agent

• procmail, maildrop

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

• sendmail and Postfix– 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.

MTA’s

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

Dovecot Configuration Filehttp://wiki.dovecot.org/QuickConfiguration

• /etc/dovecot.conf– protocols = pop3 pop3s imap imaps– listen = 10.161.25.131:10100– #ssl listen = 10.161.25.131:10943– For POP3S and IMAPS support

• #ssl_disable = no

– Activating Dovecot• chkconfig dovecot on• service dovecot start

sendmail Configurationhttp://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

• sendmail.cf• mail configuration file

• sendmail.mc • 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 jblow@what.com to

jblow@who.com

• statistic• 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 email forwarding for users outside of your

network

• Basic Directives in sendmail.mc• DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, 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:10.161 RELAY

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