Mailjet is a third-party global email service that offers Compute Engine usersa free tier with 6,000 emails each month. In addition, Mailjet also offers:

• An API, user interface, and SMTP relay to send transactional and marketingemail.
• European data privacy compliance.
• Email and deliverability features, such as customizable priority settings andautomated throttle management.
• API resource library in Go, PHP, Nodejs, Java, Python, and Ruby to managesub-accounts, authentication, contacts, campaigns, custom payloads,statistics, real time events, and parsing through theEvent API.
• IntegratedMJML framework tocreate responsive HTML email templates.
• 24/7 follow-the-sun support in 4+ languages.
• Ability to send email messages from domains other thangmail.com.

This document describes how to configure your VM instance to send mail throughMailjet using the following methods:

• Through anSMTP relay with:
  • Postfix
  • Nodemailer onNode.js
• Directly through the Mailjet API using Java

For extensive documentation of other email solutions, including examples ofintegration with most common SMTP servers, libraries, and frameworks, seeMailjet's documentation.

Before you begin

1. Create a new Mailjet account on Mailjet'sGoogle partnerpage*.When signing up, provide the domain and email address from which you want tosend email messages.

2. Get your Mailjet SMTP account credentials.

3. Make sure the email address you want to send emails from has beenvalidated.

4. Set up a firewall ruleto allow TCP traffic on port 2525.

^{* Google is compensated for customers who sign up for a non-free account.}

Configuring Mailjet as an SMTP relay

Configuring Mailjet as a mail relay lets you forward email messages to Mailjetfor remote delivery.

Using Postfix

1. Connect to your VM using SSH, replacinginstance-name with the name of the instanceyou want to send email messages from:

   gcloud compute sshinstance-name

2. On the VM, install the Postfix Mail Transport Agent. When prompted,accept the default choices for domain names but select theLocal Onlyconfiguration.

   Debian

   sudo apt update && sudo apt -y install postfix libsasl2-modules

   CentOS

   sudo yum install postfix cyrus-sasl-plain cyrus-sasl-md5 -y

3. Modify the Postfix configuration options. Postfix configuration options areset in themain.cf file. Open the file with the text editor of yourchoice:

   sudo vi /etc/postfix/main.cf

4. Update the file:

   1. Comment out the following lines:

      # default_transport = error# relay_transport = error

   2. Add the following lines to the end of the file:

      relayhost = in-v3.mailjet.com:2525smtp_tls_security_level = encryptsmtp_sasl_auth_enable = yessmtp_sasl_password_maps = hash:/etc/postfix/sasl_passwdsmtp_sasl_security_options = noanonymous

      These lines enforce SSL/TLS support and configureSMTP authentication for these requests. A simple access and securitylayer (SASL) module handles authentication in the Postfix configuration.

      Note: You must use port 2525 because port 25 is not allowed onCompute Engine.

   3. Save your changes and close the file.

5. Create the SASL password map with the text editor of yourchoice:

   sudo vi /etc/postfix/sasl_passwd

6. To thesasl_passwd file, add the following lines to provide the credentialsfor Mailjet:

   in-v3.mailjet.com:2525 YOUR_API_KEY:YOUR_SECRET_KEY

7. Use thepostmap utility to generate a.db file:

   sudo postmap /etc/postfix/sasl_passwdsudo ls -l /etc/postfix/sasl_passwd*

   You should receive the following response:

   -rw------- 1 root root    68 Jun  1 10:50 /etc/postfix/sasl_passwd-rw------- 1 root root 12288 Jun  1 10:51 /etc/postfix/sasl_passwd.db

8. Next, remove the file that contains your credentials because it is no longerneeded:

   sudo rm /etc/postfix/sasl_passwd

9. Set the permissions on your.db file:

   sudo chmod 600 /etc/postfix/sasl_passwd.dbsudo ls -la /etc/postfix/sasl_passwd.db

10. Finally, reload your configuration to load the modified parameters:

    Debian

    sudo /etc/init.d/postfix restart

    CentOS

    sudopostfixreload

11. Test your configuration. Install themailx ormailutils package and testyour configuration.

    Debian

    sudo apt -y install mailutils

    CentOS

    sudo yum install mailx -y

    Send a test message:

    echo 'Test passed.' | mail -s 'Test-Email' -aFrom:from-emaildestination-email

    Replace the following:

    • from-email: An email address that has beenvalidated.
    • destination-email: The address to send theemail message to.

    Look in your system's logs for a status line containingstatus and thesuccessful server response code(250):

    Debian

    sudotail-n5/var/log/syslog

    CentOS

    sudotail-n5/var/log/maillog

If you run into issues setting up Postfix with Mailjet, see theMailjet Postfix setup instructions.

Using Nodemailer

The following instructions describe how to use Mailjet with Node.js on DebianWheezy.