Setup Remote SMTP Server for OpenPanel

To set up a remote SMTP server for all emails sent from OpenPanel user websites, follow these steps:

Whitelist the Remote SMTP Server​

On the server with OpenPanel installed, ensure that the IP address of the remote SMTP server is whitelisted on firewall.

Similarly, on the remote SMTP server, make sure to whitelist the IP address of the OpenPanel server.

Configure SMTP per User​

For each user, SMTP settings are configured via the /etc/msmtprc file. An example file content is shown below:

# /etc/msmtprc
defaults
auth       off
tls        off
logfile    /var/log/msmtp.log

account    default
host       openadmin_mailserver
port       25
from       USERNAME@HOSTNAME

Login as root for that user and edit the file. In this file, set the email address and server to be used for all outgoing emails.

For example, you can configure Gmail SMTP settings as shown in the Arch Linux Wiki.

Example configuration for Gmail:

# Set defaults.
defaults

# Enable or disable TLS/SSL encryption.
auth on
tls on
tls_certcheck off

# Set up a default account's settings.
account gmail
logfile /var/log/msmtp.log
host "smtp.gmail.com"
port 587
user email_account_here@gmail.com
password "password_here"
from "email_account_here@gmail.com"

# Set default account
account default: gmail

Example configuration for OpenPanel MailServer using a specific email account:

# Set defaults.
defaults

# Enable or disable TLS/SSL encryption.
#auth on
tls off
tls_certcheck off
#auth plain

# Set up a default account's settings.
account USERNAME
logfile /home/USERNAME/msmtp.log
host openadmin_mailserver
port 25
user "email_account_here@example.com"
password "password_here"
from "email_account_here@example.com"

# Set default account
account default: USERNAME

After saving the configuration, test sending emails from a PHP website like WordPress or directly from the terminal: Simple PHP Mail test

Configure SMTP for all existing users​

Create a new file on the server, and in it copy the default /etc/msmtprc file.

In the file set your remote SMTP server address and optionally logins.

When finished, run the bellow command to copy the file to each OpenPanel user:

  for user in $(opencli user-list --json | grep -v 'SUSPENDED' | awk -F'"' '/username/ {print $4}'); do
    echo "Processing user: $user"
    docker cp filename $user:/etc/msmtp
  done

Configure SMTP automatically for new users​

To automatically have all users pre-configured to use your remote SMTP server, build a docker image that has your custom /etc/msmtprc file.