Postfix is an excellent and simple way to run your mail system. I switched from an old version of Exim, as the configurations were just too much to deal with. I hear the newer Exims are a bit better, but I haven't tried them. Postfix is fairly standard these days, so unless you have specific mail system requirements, you can't go wrong with it.
Choose postfix, then 'OK'. Postfix is now installed, with all the necessary configuration files in /etc/postfix. It's also been installed as a service, which I love so much. Start 'er up:
Log out of your root session.
Since I run multiple web sites, but only have a few people who actually use the system for mail, I set up both virtual aliases and virtual mailboxes. For instance, I might host a small-business website, and they'll want a bunch of email addresses for their store, but I don't want them to have a user account on the machine. Virtual mailboxes to the rescue. Virtual aliases allow me to have the same address at different domains go to different mailboxes as well, which is handy from a user and maintenance perspective, and also for reducing spam (bob@domain1.com will go to a different place than bob@domain2.com). The key directives to set are in /etc/postfix/main.cf:
#Blank, for virtual domains
mydestination =
#Blank, for virtual domains
local_recipient_maps =
#Some helpful spam settings
smtpd_helo_required = yes
smtpd_helo_restrictions =
smtpd_sender_restrictions =
# hash:/etc/postfix/access
smtpd_data_restrictions =
#Other tweaks
max_idle = 300s
anvil_status_update_time = 1h
anvil_rate_time_unit = 300s
export_environment = TZ MAIL_CONFIG SENDER
Virtual mailboxes and aliases are acheived by adding all the following directives (at the end of main.cf):
With all those virtual settings, we'd better set up what it needs in the real system. Still as root, run the following:
For each domain you want to accept mail at:
Each virtual user should have a spool file, and then you can point all the email addresses you want at it. Edit /etc/postfix/vmailbox
That puts the spool file for 'blake' into /var/mail/vhosts/mydomain.com/blake. If I want aliases to go to that spool, point them at my main email address by editing /etc/postfix/virtual.hash:
When you're all done setting up mailboxes and aliases, run postmap on each file:
This was a bit complex and it took me a long time to get right for my particular set up. Remember, this guide is pretty much a giant notepad for me to keep track of all my linux sysadmin fun! You can probably safely ignore this part if you want, unless you also need special piping procedures. While ensuring that I have virtual aliases and mailboxes, I also had to set up a special transport to allow incoming mail to a special address to be piped to a web script. That's the transport_maps setting below, which also goes into the main.cf file:
Now, at the very bottom of the ever-so-fun /etc/postfix/master.cf (not main.cf), I created a transport named "mycatch":
Almost there. Now we just have to set up the specific address in /etc/postfix/transport, like so:
Note that these addresses also have to be set up in the virtual mailbox file as well, as the addresses need to be recognized. Transports happen after mail acceptance, but before delivery, so the email needs to be valid (ie. in the mailbox file) in order for it to be accepted. Edit /etc/postfix/vmailbox:
Note that the mail will never be delivered to the devnull mailbox, as the transport we just set up will intercept it. You get the idea. Now run:
and try out your pipe scripts by sending an email.
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