Set up your own mailbox with Mail-in-a-Box

Mail-in-a-Box installs a complete mail server (Postfix, Dovecot, Roundcube webmail, DNS, Let's Encrypt SSL, spam filtering and an admin panel) from a single script.

WARNING

Running a mail server is ongoing work: DNS, reverse DNS (PTR), SPF/DKIM/DMARC and IP reputation all matter for deliverability. Plan for that before pointing a real domain at it.

Prerequisites

• A Gigahost VPS with Ubuntu 22.04 LTS.
• At least 1 GB RAM (2 GB recommended).
• A domain name you control.
• Reverse DNS (PTR) for the server's primary IPv4 set to your mail hostname (mail.example.com). Set it in the Reverse DNS field on the server's Network tab. For IPv6, see Set up reverse DNS (PTR) on a routed /48 IPv6.

Step 1: point your domain at the server

In your domain registrar's DNS panel, add an A record:

Field	Value
Host	mail
Type	A
Points to	Your server's primary public IPv4

Wait for DNS to propagate: a few minutes to a few hours, depending on the TTL.

TIP

Mail-in-a-Box prefers to be the authoritative DNS server for your domain, so it can manage SPF/DKIM/DMARC for you. After installation you will be told which nameservers to delegate to. If you keep DNS elsewhere, you will need to copy those records by hand.

Step 2: connect to the server

ssh root@your_server_ip
apt update && apt upgrade -y

Step 3: run the installer

curl -s https://mailinabox.email/setup.sh | sudo bash

It prompts for:

• An admin email address.
• The hostname (e.g. mail.example.com).
• Confirmation of the public IP.

The whole installation takes 10-15 minutes.

Step 4: open the admin panel

When the installer finishes, browse to:

https://mail.example.com/admin

Log in with the admin email + password set during install.

Step 5: create a mailbox

In the admin panel, go to Mail → Users, enter the email address (e.g. [email protected]) and a password, and click Add User.

Step 6: configure a mail client

IMAP

Setting	Value
Server	mail.example.com
Port	993
Encryption	SSL/TLS
Username	full email address
Password	your mailbox password

SMTP (submission)

Setting	Value
Server	mail.example.com
Port	587
Encryption	STARTTLS
Auth	Required

Step 7: verify deliverability

In the admin panel: System → Status Checks.

Make sure the report is green for:

• SPF record present and valid.
• DKIM signing key published.
• DMARC record set.
• SSL certificate valid for the mail hostname.
• PTR (rDNS) matches the server's hostname.

Mail-in-a-Box configures most of these for you, but the PTR record on your IPv4 has to be set in Flux (see Prerequisites).

Step 8: harden the host

At minimum:

• Disable root SSH login and password auth. See Secure your Linux server.
• Enable unattended-upgrades so security patches land on their own.
• Use strong passwords on every mailbox.
• Enable 2FA on the admin panel if available.

Backups

Mail-in-a-Box makes encrypted nightly backups. In the admin panel you can point them at an external destination (e.g. S3-compatible object storage) and restore from them. For mail you rely on, keep a periodic off-host copy as well.