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Mail Server
I need a simple, lightweight mail server to gather together system reports and alerts. This will not be exposed to the Internet. It will neither be able to send or receive messages from the outside world.
Preparing the Mail Server Jail
1. Log in to your TrueNAS server as root using SSH or the Shell option of the TrueNAS Web Portal.
2. Make some decisions and define some variables.
# Tailor each of these examples for your own situation JAIL_NAME="net" # name of the jail that will contain the mail server
Set up the Mail Delivery Agent
I will be using the simple sendmail service that comes as standard with BSD installations. It just needs to be configured and started. I don't need any clever security, as it can only be accessed from the LAN, and I'm not going to tell it how to pass messages on to the outside world.
1. Build the initial configuration
jexec "ioc-${JAIL_NAME:?}" /bin/sh -c "cd /etc/mail && make"
2. Define the default mailbox where all system messages are sent.
The domain name (the bit after the @ sign in the email address) can be localhost, or the domain name you set up when you created this jail. If it is omitted, it will default to localhost. This is ok for emails between users of the same jail.
The user name will be the same as the mailbox name (the bit before the @ sign). You will need to create a new user login, and assign a password, in the usual way.
In this example I will be creating a mailbox called “administrator”.
jexec "ioc-${JAIL_NAME:?}" adduser
Username: administrator Full name: System Administrator Uid (Leave empty for default): Login group [administrator]: staff Login group is staff. Invite administrator into other groups? []: Login class [default]: Shell (sh csh tcsh bash rbash git-shell netcli.sh ksh93 mksh zsh rzsh scponly nologin) [sh]: nologin Home directory [/home/administrator]: Home directory permissions (Leave empty for default): Use password-based authentication? [yes]: Use an empty password? (yes/no) [no]: Use a random password? (yes/no) [no]: Enter password: ***** Enter password again: ***** Lock out the account after creation? [no]: Username : administrator Password : ***** Full Name : System Administrator Uid : 1001 Class : Groups : staff Home : /home/administrator Home Mode : Shell : /usr/sbin/nologin Locked : no OK? (yes/no): yes adduser: INFO: Successfully added (administrator) to the user database. Add another user? (yes/no): no Goodbye!
jexec "ioc-${JAIL_NAME:?}" vi /etc/mail/aliases
On the first page, find the lines like this…
# Pretty much everything else in this file points to "root", so # you would do well in either reading root's mailbox or forwarding # root's email from here. # root: me@my.domain
After that, insert a new line like this…
root: mailbox
—
jexec "ioc-${JAIL_NAME:?}" sysrc sendmail_enable="NO"
jexec "ioc-${JAIL_NAME:?}" sysrc sendmail_outbound_enable="NO"
jexec "ioc-${JAIL_NAME:?}" sysrc sendmail_submit_enable="YES"
jexec "ioc-${JAIL_NAME:?}" sysrc sendmail_msp_queue_enable="YES"
jexec "ioc-${JAIL_NAME:?}" service sendmail restart
Set up the POP Mailbox Service
I need to be able to view messages on my workstation using a normal mail reader. The messages I receive will be actioned and then deleted. I don't need the clever folders that IMAP provides, so I'll just use the POP protocol to access the mailbox.
Initially I just want one mailbox for all notifications from the various devices across my LAN. This can easily be configured by creating a normal Unix user on the mail server box. They don't need to be able to log in, but the normal passwd and shadow files will store all the configuration we need for each mailbox. The root login and other system logins will be set to forward their mail to my special email address on the same host.
Set up Thunderbird to access the Mailbox
Credits
This page has been cobbled together from various bits of information I've found on the Internet.