How to Install Simple NixOS Mailserver on OpenBSD

In this tutorial, we will explain how to install Simple NixOS Mailserver on OpenBSD. Simple NixOS Mailserver is a suite of software that allows you to run your own mail server. This tutorial assumes that you have a basic understanding of OpenBSD and know how to access the command line.

Prerequisites

• A server running OpenBSD
• A domain name pointed to the server
• A valid SSL certificate

Step 1: Install required packages

The first step is to install the required packages on the OpenBSD server. Run the following command to install the packages:

doas pkg_add git gnupg curl postfix dovecot opendkim opendmarc rspamd certbot

Step 2: Install Simple NixOS Mailserver

Next, we need to install Simple NixOS Mailserver. Follow the steps below:

1. Clone the Simple NixOS Mailserver repository using the command:

git clone https://gitlab.com/simple-nixos-mailserver/nixos-mailserver.git

2. Change the directory to the cloned repository:

cd nixos-mailserver

3. Import the Simple NixOS Mailserver public GPG key:

curl -sSL https://keybase.io/simple-nixos-mailserver/pgp_keys.asc | doas gpg --import

4. Verify that the key has been imported correctly:

doas gpg --fingerprint BBE88A6FCB7E49A9C9B7CF319CFE6A9407F47B4E

5. Run the Simple NixOS Mailserver installation script:

./install.sh

Step 3: Configure the Mailserver

After the installation is complete, we need to configure the mail server. Follow the steps below:

1. Edit the mail-config-example.nix file:

doas vim mail-config-example.nix

2. Modify the following settings in the file:

• Change mydomain.com to your domain name
• Modify the users block to include the email addresses you want to use
• Add any aliases in the aliases block

3. Save and close the file

4. Generate the configuration file:

./generate-config.sh mail-config-example.nix > mail-config.nix

5. Apply the configuration changes:

sudo nixos-rebuild switch

Step 4: Configure and Start Rspamd

Rspamd is the spam filter used by Simple NixOS Mailserver. We need to configure and start Rspamd using the following steps:

1. Edit the rspamd/local.d/worker-controller.inc file:

sudo vim /etc/rspamd/local.d/worker-controller.inc

2. Modify the bind_socket setting to listen on localhost:

bind_socket = "localhost:11333";

3. Save and close the file

4. Enable the Rspamd service:

sudo systemctl enable rspamd.service

5. Start the Rspamd service:

sudo systemctl start rspamd.service

Step 5: Configure and Start Postfix

Postfix is the SMTP server used by Simple NixOS Mailserver. We need to configure and start Postfix using the following steps:

1. Edit the mail-config.nix file:

sudo vim /etc/nixos/mail-config.nix

2. Modify the smtpd_sasl_auth_enable setting to yes:

smtpd_sasl_auth_enable = "yes";

3. Save and close the file

4. Enable the Postfix service:

sudo systemctl enable postfix.service

5. Start the Postfix service:

sudo systemctl start postfix.service

Step 6: Configure and Start Dovecot

Dovecot is the IMAP and POP3 server used by Simple NixOS Mailserver. We need to configure and start Dovecot using the following steps:

1. Edit the mail-config.nix file:

sudo vim /etc/nixos/mail-config.nix

2. Modify the protocols setting to include IMAP and POP3:

protocols = [ "imap" "pop3" ];

3. Save and close the file

4. Enable the Dovecot service:

sudo systemctl enable dovecot.service

5. Start the Dovecot service:

sudo systemctl start dovecot.service

Step 7: Configure DKIM and DMARC

DKIM and DMARC are email authentication mechanisms that help prevent email spoofing. We need to configure and start DKIM and DMARC using the following steps:

1. Edit the mail-config.nix file:

sudo vim /etc/nixos/mail-config.nix

2. Add your DKIM selector and key file path under opendkim.keys

3. Modify the opendmarc.report_email setting to your email address:

opendmarc.report_email = "you@yourdomain.com";

4. Save and close the file

5. Enable the opendkim and opendmarc services:

sudo systemctl enable opendkim.service
sudo systemctl enable opendmarc.service

6. Start the opendkim and opendmarc services:

sudo systemctl start opendkim.service
sudo systemctl start opendmarc.service

Step 8: Configure SSL Certificate

Simple NixOS Mailserver requires an SSL certificate to secure the email traffic. We need to configure the SSL certificate using the following steps:

1. Generate a new SSL certificate or obtain a trusted one

2. Edit the mail-config.nix file:

sudo vim /etc/nixos/mail-config.nix

3. Modify the sslCertificate and sslPrivateKey settings to the path of your SSL certificate and private key respectively:

sslCertificate = "/path/to/ssl/cert";
sslPrivateKey = "/path/to/ssl/private/key";

4. Save and close the file

5. Apply the configuration changes:

sudo nixos-rebuild switch

Conclusion

Congratulations! You have successfully installed Simple NixOS Mailserver on OpenBSD and configured it to run a mail server. You can now start sending and receiving emails from your own mail server.

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