Mailpit is an alternative to MailHog. It is a hosted SMTP server. Instead of sending emails to recipients, it captures and stores all emails for inspection via web UI. This is useful for testing applications in staging and development environments.
Approach
Mailpit provides a shell script for installation. It just downloads the latest binary and copies it to /usr/local/bin/mailpit. It lacks configurations for Systemd and Apache web server. If you prefer docker, there are instructions for that. I prefer a manual setup, which involves building from source.
Prerequisites
Make sure the following software is installed:
Building
TIP: You can skip this step if you use the shell script for installation.
The application is developed in Go and npm is also required to build the web UI. Checkout out the source code from https://github.com/axllent/mailpit.git and navigate to the root folder of the source code.
npm install
npm run build
go build -ldflags "-s -w"
sudo cp ./mailpit /usr/local/bin/
Create Password File
The web UI and API uses Basic Authentication, but it is optional. SMTP authentication is also optional. I recommend enabling authentication for both web and SMTP access. Credentials are generated using htpasswd and stored in a file in any location. Web and SMTP can use separate credential files. For simplicity, I will use the same file for both.
sudo mkdir -p /etc/mailpit/htpasswd
sudo htpasswd -c /etc/mailpit/htpasswd bob123
sudo chmod 600 /etc/mailpit/htpasswd
NOTE: Whenever there are changes to the credential file, the Mailpit server must be restarted for the change to take effect.
Create Systemd Service File
Create a Systemd service file, /etc/systemd/system/mailpit.service.
[Unit]
Description=Email testing tool
Documentation=https://github.com/axllent/mailpit
After=network.target
[Service]
Type=simple
ExecStart=/usr/local/bin/mailpit --ui-auth-file /etc/mailpit/htpasswd --smtp-auth-file /etc/mailpit/htpasswd --smtp-auth-allow-insecure --db-file /tmp/mailpit.db
Restart=on-failure
RestartSec=5s
[Install]
WantedBy=multi-user.target
NOTE: Emails are stored in an SQLite file. As specified in /usr/lib/tmpfiles.d/tmp.conf, files in /tmp/ will be deleted every 10 days. If you want to keep the database persistent, you may consider storing it in other places, e.g. /var/lib/mailpit/.
Enable and start the service.
sudo systemctl enable mailpit
sudo systemctl start mailpit
The web UI will be available at http://127.0.0.1:8025 (not accessible from the public). SMTP service will be available at 0.0.0.0:1025.
Reverse Proxy On Apache Web Server
Create a config file at /etc/httpd/conf.d/mailpit.example.com.conf.
<VirtualHost *:80>
ServerName mailpit.example.com
ProxyPass / http://localhost:8025/
ProxyPassReverse / http://localhost:8025/
CustomLog logs/mailpit.example.com-access.log combined
ErrorLog logs/mailpit.example.com-error.log
</VirtualHost>
ServerName directive is not required if this is the only site hosted on the server. It is needed if the server is hosting multiple sites with different domain names. SSL is recommended (extra configuration is needed).
Restart the Apache web server.
sudo systemctl reload httpd
Usage
Set the SMTP configuration in your application with the following information:
Host: <domain name of IP of server>
Port: 1025
Username: <defined in /etc/mailpit/htpasswd>
Password: <defined in /etc/mailpit/htpasswd>
