Installing Mailhog

Mailhog is similar to MailTrap in that it intercepts all email messages being sent from your application and displays them in a simple web interface. Mailhog is currently used by the Elentra Developer Docker environment to facilitate email testing by developers.

If you need to test features in Elentra that send out emails in your Development / Staging / Test environments, then the following instructions will help you install Mailhog on your servers.

Install Go

To install Go, you will need to connect to your web server and execute the following commands:

wget https://go.dev/dl/go1.21.1.linux-amd64.tar.gz
sudo tar -C /usr/local -xzf go*.linux-amd64.tar.gz
vi /etc/profile

Add the following line at the bottom of the /etc/profile file.

export PATH=$PATH:/usr/local/go/bin

Save and exit the file. Refresh the path, exit out of superuser mode and verify that go is installed:

source /etc/profile
go version

Reference: computingforgeeks.com

Install Mailhog

Run the following to install and run the Mailhog server:

go install github.com/mailhog/MailHog@latest
cp ~/go/bin/MailHog /usr/local/bin/Mailhog
Mailhog

You may need to exit out of your SSH connection, and then SSH back into the server before running Mailhog.

Leave Mailhog running from the command line until you have finished installing and testing mhsendmail below. (Later we will add mailhog as a service that runs in the background automatically, so this is only needed temporarily.)

To access the Mailhog interface, use your browser to navigate to port 8025 on the web server. e.g. http://staging.elentra.med.university.edu:8025

If the server is behind a load balancer, then you will either need to open up that port on the web server, or use the web server machine name instead of the URL above.

Reference: gist

Install mhsendmail

mhsendmail is a sendmail replacement that will ensure that all emails are routed to Mailhog.

Clone and build mhsendmail:

git clone https://github.com/mailhog/mhsendmail.git
cd mhsendmail
go mod init
go get github.com/mailhog/mhsendmail/cmd
go mod vendor
go build
sudo mv mhsendmail /usr/local/bin/mhsendmail

The current release tags of mhsendmail (v0.2.0 and earlier) do not support the -t flag. The master branch of mhsendmail is required to allow the -t flag.

To test mhsendmail, you can copy and paste the following at the command prompt:

mhsendmail -t [e-mail] <<EOF
From: App <[e-mail]>
To: Test <[e-mail]>
Subject: Test message
 
Some content!
EOF

At this point you should be able to see this message in Mailhog in your web browser.

Reference: mailtrap.io

Replace sendmail with mhsendmail

Next we need to make the system use mhsendmail instead of sendmail. (This is so we are sure that emails are sent to Mailhog and don't get out into the wild.)

Update php.ini

On the web application server edit the php.ini file.

cd /etc/
sudo vi php.ini

Search for sendmail_path. Comment out the existing entry and add a new entry.

sendmail_path = "/usr/local/bin/mhsendmail -t --smtp-addr=localhost:1025"

Save and close the file. Restart the supervisord service, to reload php.ini:

sudo systemctl restart supervisord

Reference: gist

Update sendmail path in settings file

Elentra also uses the sendmail path specified in the settings-xxx.inc.php files. Change the SENDMAIL_PATH constant in the settings-staging.inc.php file as follows.

define("SENDMAIL_PATH", "/usr/local/bin/mhsendmail -t -i --smtp-addr=localhost:1025");

Save the file, commit, then deploy the change.

Set up Mailhog as a Service

Once you have Mailhog installed and Elentra pointed to it for sending mail, you will want to set up a Service to restart Mailhog when the server reboots.

If you have Mailhog manually running from the command line, you will want to exit out of it at this point.

Create a new Mailhog service:

sudo tee /etc/systemd/system/mailhog.service <<EOL
[Unit]
Description=Mailhog
After=network.target
[Service]
User=$USER
ExecStart=/usr/bin/env /usr/local/bin/Mailhog > /dev/null 2>&1 &
[Install]
WantedBy=multi-user.target
EOL

Start the service by issuing the following command.

sudo systemctl restart mailhog

To verify that the service is running, issue the following command.

sudo systemctl status mailhog

Reference: gist