Postfix Revision as of Sunday, 20 December 2015 at 19:56 UTC
Written for CentOS 6.4, Postfix 2.6.6
Overview
Things were easier to set up after understanding these things, even
cursorily.
Mail Transfer - Basic Idea
Lots of formal abbreviations!
Sender > Server > Server > ... > Server > Receiver
(MUA) (MTA) (MTA) (MTA) (MUA)
You can be a bit more granular:
Sender > Server > Server > ... > Server > Receiver
(MUA > MSA > MTA) (MTA) (MTA > MDA > MRA > MUA)
This separation of purpose is good since you can use variety of
applications at each stage. Lot of possibilities. E.g.
Sender > Postfix > Procmail > Clam Anti-Virus > SpamAssassin > Procmail > Receiver
(MUA) (MTA) ( MDA ) (MUA)
Open Relays
Where it is not required to (1) authenticate to your server, and/or (2)
be in the same network as the server to send email. This is very bad for
public-facing mail servers. From a simpler time when there were very few
email servers and everybody was nice to each other.
Installation
yum install postfix
ln -s /usr/sbin/sendmail.postfix /etc/alternatives/mta --force
Configuration
Working with /etc/postfix/main.cf.