Learn Mailserver - Prerequisite Skills & Environment Setup

#Introduction

Welcome to the Learn Mailserver series! Over the next 23 episodes we'll build a complete self-hosted mail server: Postfix as the MTA, Dovecot as the IMAP/POP3 server, and Roundcube as webmail — from zero all the way to production-grade.

Episode 0 is pure foundation. No packages are actually configured yet; we make sure you have enough skills, a capable environment, and a domain that's ready to use. The real installation begins in episode 3.

We'll cover three things: the core skills you must master, the hardware and software requirements for our lab, and the environment verification steps before you begin.

#Core Skills You Must Master

A mail server is not an "install and forget" application. It lives at the intersection of operating systems, networking, and DNS. Without the following four foundations, debugging will feel like fumbling in the dark.

#Linux CLI and Service Administration

Every component runs as a Linux service. At minimum, master these:

File navigation and manipulation with cd, ls, cp, mv, and rm.
Service management with systemctl — you'll use it to check the status of Postfix, Dovecot, and friends.
Package installation via apt (Debian/Ubuntu) or dnf (RHEL family).
Reading logs with journalctl, tail, and grep.

#DNS and Domain Management

Email runs on top of DNS: the destination mail server is found via the MX record, identity is verified via the TXT records SPF/DKIM/DMARC, and reputation is measured through the PTR record. You need to be comfortable adding records in your registrar's or DNS provider's panel, and verifying them with dig or host.

#TLS and Certificates

SMTP, IMAP, and webmail all use TLS. Learn the concept of key pairs (private key + public key), certificates, and how to get free certificates from Let's Encrypt via certbot. Episode 6 will break this down thoroughly.

#SMTP and IMAP Basics

You don't need to memorize the RFCs, but you must understand the big picture: SMTP for sending and receiving email between servers, IMAP/POP3 for clients retrieving email from mailboxes, plus the terms MTA, MDA, and relay. Episode 2 will map out the full architecture.

Note

Don't panic if some terms are still unfamiliar. Episode 0 introduces the map; episodes 1 through 22 will break down each concept. What you must take away from here is a basic acquaintance, not full mastery.

#Hardware and Software to Prepare

The good news is that a mail server doesn't need a big machine. One small VPS is more than enough for small-scale production.

Requirement	Recommendation	Role in the Series
VPS/Dedicated	2 vCPU, 2-4 GB RAM, 40-80 GB disk	Runs all components
OS	Debian 12 or Ubuntu 24.04	The smoothest environment for this series
Domain	One domain + DNS registrar access	Example `example.com` throughout the series
DNS	A, MX, SPF, DKIM, DMARC, PTR	The foundation of deliverability
Database	MariaDB/PostgreSQL (optional)	Virtual users backend in episode 7
TLS	Let's Encrypt + `certbot`	Free certificates for all services

All components — Postfix, Dovecot, Roundcube, MariaDB, and Amavis — can run on a single VPS. That's exactly the pattern used by the most common homelab and SMB setups in the real world.

#Domain and DNS Access

Choose a domain over which you have full control of DNS. Not a subdomain of someone else's service, and not a domain used by other people. For this series we consistently use example.com and the host mail.example.com.

Make sure the A record for mail.example.com points to your VPS's public IP. Check before moving on:

Verify mail host A record

dig A mail.example.com +short
host example.com

If the output is empty, the record hasn't propagated yet or there's a typo. Fix it first — the entire lab stands on top of this address.

#VPS with a Clean IP and rDNS

Your IP's reputation decides the fate of your email. Choose a VPS that provides a clean IP — meaning an IP not listed on email blacklists. Check blacklist history with online tools such as MXToolbox before ordering.

Equally important is the rDNS/PTR record: your VPS's IP must resolve back to mail.example.com. Many providers offer this feature from the panel. Verify:

Check rDNS/PTR of VPS IP

dig -x 203.0.113.10 +short

Replace 203.0.113.10 with your VPS's IP. If the result isn't mail.example.com, configure it through the provider's panel. A wrong rDNS is a classic cause of email landing in spam.

#Setting Up the Environment

Before closing the episode, make sure the essential tools are installed and SSH is working:

Check versions of core tools

postconf mail_version
dovecot --version
openssl version

The first line prints the Postfix version — 3.11.5 for the latest 2026 repositories — the second shows Dovecot CE 2.4.4, and the third the OpenSSL version. Episode 21 will discuss the meaning of these version numbers in depth.

If postconf or dovecot aren't present yet, that's fine — episodes 3 and 4 install them. What matters now: SSH into the VPS works, sudo runs, and the internet connection is stable.

#Verification Checklist

Before moving to episode 1, make sure everything is green:

VPS is active with a public IP and rDNS pointing to mail.example.com.
Domain and DNS registrar access are ready.
dig A mail.example.com returns your VPS IP.
SSH and sudo work on the VPS.
postconf mail_version and dovecot --version can be run.

If all of these pass, your environment is officially ready to be built.

#Conclusion

Episode 0 is done. Here's what to take with you:

Master the Linux CLI, service administration, DNS, TLS, and the basics of SMTP/IMAP.
Prepare a VPS with a clean IP and configured rDNS.
Use a single domain over which you have full DNS control.
Verify the A record and PTR record before you start.
Make sure postconf and dovecot can be run from the terminal.

Next, in episode 1 we step back for a moment to answer the most fundamental question: how email was born, where Postfix, Dovecot, and Roundcube come from, and what problems they actually solve. See you there!