Sending email with SendGrid

This tutorial shows how to use SendGrid to send email from an app running on a Compute Engine instance. SendGrid is a third-party email service that offers Compute Engine users a free trial with 12,000 transactional emails free each month.

Objectives

  • Use SendGrid with Postfix on a Compute Engine instance.
  • Use SendGrid in Java code running on a Compute Engine instance.
  • Use SendGrid in Node.js code running on a Compute Engine instance.

Costs

This tutorial uses billable components of Google Cloud including Compute Engine.

New Google Cloud users might be eligible for a free trial.

Before you begin

  1. Sign in to your Google Account.

    If you don't already have one, sign up for a new account.

  2. In the Cloud Console, on the project selector page, select or create a Cloud project.

    Go to the project selector page

  3. Make sure that billing is enabled for your Google Cloud project. Learn how to confirm billing is enabled for your project.

  4. In the Cloud Console, go to the VM Instances page.

    Go to the VM Instances page

  5. Click Create instance.
  6. Set Name to sendgrid-tutorial.
  7. In the Boot disk section, click Change to begin configuring your boot disk.
  8. On the Public images tab, choose a Debian or CentOS image version.

  9. Click Select.
  10. Click Create to create the instance.
  11. Use the Google Cloud Marketplace to sign up for the SendGrid email service. Make a note of your SendGrid SMTP account credentials, which include username, password, and hostname. Your SMTP username and password are the same as what you used to sign up for the service. The SendGrid hostname is smtp.sendgrid.net.
  12. Create an API key:
    1. Sign in to SendGrid and go to Settings > API Keys.
    2. Create an API key.
    3. Select the permissions for the key. At a minimum, the key must have Mail send permissions to send email.
    4. Click Save to create the key.
    5. SendGrid generates a new key. This is the only copy of the key, so make sure that you copy the key and save it for later.

Sending mail from your instance with Postfix

Complete the following steps to connect to your sendgrid-tutorial instance and run SendGrid with Postfix.

Connect to your sendgrid-tutorial instance using SSH

  1. In the Cloud Console, go to the VM instances page.

    Go to the VM instances page

  2. In the list of virtual machine instances, click SSH in the row of the instance that you want to connect to.

Configuring SendGrid as an SMTP relay with Postfix

Run the following commands in your SSH terminal to use SendGrid as an SMTP relay with Postfix.

  1. Become a superuser:

    sudo su -
    
  2. Set a safe umask:

    umask 077
    
  3. Install the Postfix Mail Transport Agent:

    Debian

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

    CentOS

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

    If prompted, select the Local Only configuration and accept the default domain name.

  4. Modify the Postfix configuration options. Open /etc/postfix/main.cf for editing. For example, to use the nano text editor, enter the following command:

    nano /etc/postfix/main.cf
    
  5. 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 = [smtp.sendgrid.net]:2525
      smtp_tls_security_level = encrypt
      smtp_sasl_auth_enable = yes
      smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
      header_size_limit = 4096000
      smtp_sasl_security_options = noanonymous
      

      The above lines enforce SSL/TLS support and configure SMTP authentication for these requests. A simple access and security layer (SASL) module handles authentication in the Postfix configuration.

  6. Save and close the file.

  7. Generate the SASL password map using the API key you generated in the Before you begin section. Replace your-api-key with the API key you generated.

    echo [smtp.sendgrid.net]:2525 apikey:your-api-key >> /etc/postfix/sasl_passwd
  8. Use the postmap utility to generate a .db file:

    postmap /etc/postfix/sasl_passwd
    
  9. Verify that you have a .db file:

    ls -l /etc/postfix/sasl_passwd*
    
    -rw------- 1 root root    ...  /etc/postfix/sasl_passwd
    -rw------- 1 root root    ...  /etc/postfix/sasl_passwd.db
    
  10. Remove the file containing your credentials because it is no longer needed:

    rm /etc/postfix/sasl_passwd
    
  11. Set the permissions on your .db file and verify that the other file was removed:

    chmod 600 /etc/postfix/sasl_passwd.db
    ls -la /etc/postfix/sasl_passwd.db
    
    -rw------- 1 root root    ...  /etc/postfix/sasl_passwd.db
    
  12. Reload your configuration to load the modified parameters:

    Debian

    /etc/init.d/postfix restart
    

    CentOS

    postfix reload
    

  13. Install the mailutils or mailx package:

    Debian

    apt -y install mailutils

    CentOS

    yum install mailx -y
    

  14. Send a test email:

    echo 'message' | mail -s subject email@example.com

    Replace the following:

    • message: The body of the email.
    • subject: The subject of the email.
    • email@example.com: The email address that you want to send a message to.

    Look in your system logs for a status line containing status and the successful server response code (250):

    Debian

    tail -n 5 /var/log/syslog
    

    CentOS

    tail -n 5 /var/log/maillog
    

Sending mail with Java on your instance

Connect to your sendgrid-tutorial instance using SSH

  1. In the Cloud Console, go to the VM instances page.

    Go to the VM instances page

  2. In the list of virtual machine instances, click SSH in the row of the instance that you want to connect to.

Construct and send an email message

The following instructions use the SendGrid Java client library to construct and send an email message through SendGrid. You can view the full example on GitHub.

In your SSH terminal:

  1. Become a superuser and set a safe umask:

    sudo su -
    umask 077
    
  2. Install Java and Maven:

    apt -y update && apt -y install git-core openjdk-11-jdk maven
    
  3. Clone the GitHub repo:

    git clone https://github.com/GoogleCloudPlatform/java-docs-samples.git
    
  4. Go to the main source code for the example:

    cd /root/java-docs-samples/compute/sendgrid/src/main/java/com/example/compute/sendgrid
    
  5. Open SendEmailServelet.java for editing.

    • Replace your-sendgrid-api-key with the API key for your SendGrid account.

    • Replace your-sendgrid-from-email with the email address you want to send mail from.

    • Replace destination-email with the email address you want to send mail to.

  6. Go to the root directory of the sample code:

    cd /root/java-docs-samples/compute/sendgrid
    
  7. Package the Java class:

    mvn clean package
    
  8. Go to the new target directory:

    cd target
    
  9. Set permissions that let you execute the jar file:

    chmod +x compute-sendgrid-1.0-SNAPSHOT-jar-with-dependencies.jar
    
  10. Run the alternative Java version selector:

    update-alternatives --config java
    

    Select the java-11-openjdk-amd64 option.

  11. Execute the Java file:

    java -jar compute-sendgrid-1.0-SNAPSHOT-jar-with-dependencies.jar
    

Sending mail with Node.js on your instance

To run this sample, you must have Node.js version 7.6 or later installed on the VM instance.

Connect to your sendgrid-tutorial instance using SSH

  1. In the Cloud Console, go to the VM instances page.

    Go to the VM instances page

  2. In the list of virtual machine instances, click SSH in the row of the instance that you want to connect to.

Construct and send an email message

In your SSH terminal:

  1. Become a superuser and set a safe umask:

    sudo su -
    umask 077
    
  2. Update your package repositories:

    Debian

    apt update
    

    CentOS

    yum update -y
    

  3. Install Node.js dependencies:

    Debian

    apt -y install git-core curl build-essential openssl libssl-dev
    

    CentOS

    yum install git-core curl openssl openssl-devel -y
    yum groupinstall "Development Tools" -y
    

  4. Install Node.js. By default, the installation also installs npm:

    Debian

    curl -sL https://deb.nodesource.com/setup_14.x | sudo bash -
    sudo apt -y install nodejs
    

    CentOS

    curl --silent --location https://rpm.nodesource.com/setup_14.x | bash -
    

    Then, install Node.js:

    yum -y install nodejs
    

  5. Install the SendGrid Node.js client:

    npm install sendgrid
    
  6. Clone the sample repository:

    git clone https://github.com/googleapis/nodejs-compute.git
    
  7. Go to the directory that contains the SendGrid sample:

    cd nodejs-compute/samples
    
  8. Copy the sendgrid.js file:

    cp sendgrid.js sendmail.js
    
  9. Open sendmail.js for editing.

    • Replace your-sendgrid-api-key with the API key for your SendGrid account.

    • Replace from-email@example.com with the email address that you want to send mail from.

    • Replace to-email@example.com with the email address that you want to send mail to.

    // This sample is based off of:
    // https://github.com/sendgrid/sendgrid-nodejs/tree/master/packages/mail
    const sendgrid = require('@sendgrid/mail');
    sendgrid.setApiKey(process.env.SENDGRID_API_KEY || '<your-sendgrid-api-key>');
    
    async function sendgridExample() {
      await sendgrid.send({
        to: 'to_email@example.com',
        from: 'from_email@example.com',
        subject: 'Sendgrid test email from Node.js on Google Cloud Platform',
        text:
          'Well hello! This is a Sendgrid test email from Node.js on Google Cloud Platform.',
      });
    }
    sendgridExample();

  10. Run the program to send an email message through SendGrid:

    node sendmail.js
    

Cleaning up

To avoid incurring charges to your Google Cloud Platform account for the resources used in this tutorial:

Delete the project

The easiest way to eliminate billing is to delete the project that you created for the tutorial.

To delete the project:

  1. In the Cloud Console, go to the Manage resources page.

    Go to the Manage resources page

  2. In the project list, select the project that you want to delete and then click Delete .
  3. In the dialog, type the project ID and then click Shut down to delete the project.

Delete your Compute Engine instance

To delete a Compute Engine instance:

  1. In the Cloud Console, go to the VM Instances page.

    Go to the VM Instances page

  2. Click the checkbox for your sendgrid-tutorial instance.
  3. Click Delete to delete the instance.

What's next

Try out other Google Cloud features for yourself. Have a look at our tutorials.