TL;DR why and how to setup a mail-server

Why setup a server

If you're like me you've never put much thought into your email, and you simply use a free provider.
I see three main reasons to take an alternative approach

  1. Security: Email is the backup for every other online account, and this should be in your control as much as possible.
  2. Privacy: Everything sent and received on a free provider can be read and (generally) used to target advertisements to you
  3. Customisation: With an alternative approach you can have your own address (tom@libreengineer.com instead of tom@genericprovider.com)

The server

Our mail server has to run somewhere.
In an ideal (privacy) world, this would be on self managed hardware.
However as this is the first time I've tried to put together a mail server I'd like to separate the potential software problems from the potential hardware problems.
I achieved this with an Amazon Web Services (AWS) 1GB Lightsail instance.
Debian was choses as the operating sysem as the tutorial I use recommends it. It also fits nicely with my desired for long-term stability, and free and open source software.

The software

Now that the server is setup we need to install some software on it.
But before we get there, it is probably helpful to understand the types of e-mail software and the differences.
The main terms to understand are:

  • Mail transfer agent (MTA) which implements the simple mail transfer protocol (SMTP)
  • Mail delivery agent (MDA) which implement either the internet message access protocol (IMAP) or post office protocol (POP)
    • The key difference being that POP removes emails from the server once delivered and IMAP retains them, which makes IMAP more suited to access from multiple devices.
  • Mail user agent (MUA), also known as an email client

Thinking about the steps a physical letter takes to be sent:

  1. which is written and posted into a physical postbox
  2. collected from the letterbox by the postal service
  3. the postcode is read and the letter is delivered to the appropriate post-office
  4. the address is read and the letter is delivered to the recipient's letter box
  5. the recipient collects the letter from their letter box
  6. the recipient reads the letter

For an email these steps are handling by different pieces of software, considering the sending of an email to tom@libreengineer.com.

  • MUA (email client)
    • handles steps 1, 5
    • The end-user facing aspects of email
    • writing tom@libreengineer.com into the To field
    • accessing the inbox to receive an email
  • MTA
    • handles steps 2, 3
    • The sending of emails between email servers
    • finding the IP address of libreengineer.com's mail server and sending the email there
  • MDA
    • handles step 4
    • The delivering of email from the server to an individuals inbox
    • finding tom's email location on the server and placing the email there.

In our case we will be using

  • Postfix
    • running an SMTP server as the MTA
  • Dovecot
    • running an IMAP server as the MDA
  • rspamd
    • To provide a layer of spam protection.

Setting it all up

I followed the excellent guide called 'ISPmail' put together by Christoph Haas. Which can be found at: https://workaround.org/ispmail.

Completing the picture

We now have a fully functioning mail server, which we can access via a webmail interface. To complete the picture we can also look at email clients (MUAs) for our various platforms.
In my case these are Android, where I use K-9 and Ubuntu where I use Evolution Geary.

Final thoughts

If you found this useful I'd be glad to hear from you at tom@libreengineer.com