Jonathan Teo

In the previous part of this tutorial series, we set up a mail server that could accept connections from mail clients like Gmail. This allowed us to send out domain emails using a mail client, instead of having to implement a mailbox on our server.

With our mail server’s basic functionality properly set up, we can now turn our attention to another problem — email deliverability. Spam email is a really big problem online, so many email providers have some kind of system in place to assess whether an incoming email is spam and either flag it, or reject it. Hence, after setting up our mail server, one thing we need to do is to ensure that our mail server conforms to certain email security standards, policies and protocols. This goes a long way to help us communicate to other mail servers that we are trustworthy, so that our emails will be deliverable.

In the first part of this series, we set up a basic virtual mail server with Postfix that received emails for our domain and forwarded it to a mailbox of our choice. To round off the basic set of features for our mail server, we will be setting up Simple Authentication and Security Layer (SASL) to work with Postfix, so that we can access our mail server with a mailbox client (like Gmail) and send out emails from our domain.

If you own a domain, and are looking to set up email hosting for it, you have a couple of options. You can either:

1. Get a generic web hosting service that comes with a cPanel-based email hosting service, or;
2. Use services like Google Workspace or Microsoft’s Enterprise Email Service.

The former option is cheap, but can be clunky to use and ineffective with blocking spam. The latter option — being specialised services — are generally much more accessible and effective with spam, but cost more.

There’s actually also a third option, and that is:

3. Running your own mail server on a cloud server.

This means that you have to set up the server and maintain it, but it also means that you can have a cheap and effective mail server, instead of having to choose between one or the other.

In this series of articles, we are going to explore how we can set up a virtual mail server using a Mail Transfer Agent (MTA) called Postfix. This will be a fully-featured mail server, meaning that over the course of these articles, we will be building a mail server that can:

1. Send and receive emails,
2. Filter incoming emails for spam, and;
3. Pass email policy checks, so that the emails it sends out are not flagged as spam.