Sending email with SendGrid

This tutorial shows how to use SendGrid to send email from an app running on a Compute Engine virtual machine (VM) instance.

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.
Use SendGrid with a Microsoft Exchange edge transport server on a Compute Engine instance.

For other information about setting up SendGrid, see the SendGrid developer documentation.

Costs

In this document, you use the following billable components of Google Cloud:

Compute Engine

To generate a cost estimate based on your projected usage, use the pricing calculator. New Google Cloud users might be eligible for a free trial.

Before you begin

Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Google Cloud project.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Google Cloud project.

In the Google Cloud console, go to the Create an instance page.
Go to Create an instance
Set Name to sendgrid-tutorial.
In the Boot disk section, click Change to begin configuring your boot disk.
On the Public images tab, choose a Debian or CentOS image version.
Click Select.
To create the VM, click Create.
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.
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

In the Google Cloud console, go to the VM instances page.
Go to VM instances
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.

Become a superuser:
```
sudo su -
```
Set a safe umask:
```
umask 077
```
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.
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
```
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.
Save and close the file.
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
```
Use the postmap utility to generate a .db file:
```
postmap /etc/postfix/sasl_passwd
```

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

Remove the file containing your credentials because it is no longer needed:
```
rm /etc/postfix/sasl_passwd
```

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*

-rw------- 1 root root    ...  /etc/postfix/sasl_passwd.db

Reload your configuration to load the modified parameters:
Debian
```
/etc/init.d/postfix restart
```
CentOS
```
postfix reload
```
Install the mailutils or mailx package:
Debian
```
apt -y install mailutils
```
CentOS
```
yum install mailx -y
```
Send a test email:
```
echo 'message' | mail -s subject [email protected]
```
Replace the following:
- message: The body of the email.
- subject: The subject of the email.
- [email protected]: 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

In the Google Cloud console, go to the VM instances page.
Go to VM instances
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:

Become a superuser and set a safe umask:
```
sudo su -
umask 077
```

Install Java and Maven:

apt -y update && apt -y install git-core openjdk-11-jdk maven

Clone the GitHub repo:

git clone https://github.com/GoogleCloudPlatform/java-docs-samples.git

Go to the main source code for the example:

cd /root/java-docs-samples/compute/sendgrid/src/main/java/com/example/compute/sendgrid

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.

Go to the root directory of the sample code:

cd /root/java-docs-samples/compute/sendgrid

Package the Java class:
```
mvn clean package
```
Go to the new target directory:
```
cd target
```

Set permissions that let you execute the jar file:

chmod +x compute-sendgrid-1.0-SNAPSHOT-jar-with-dependencies.jar

Run the alternative Java version selector:
```
update-alternatives --config java
```
Select the java-11-openjdk-amd64 option.

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

In the Google Cloud console, go to the VM instances page.
Go to VM instances
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:

Become a superuser and set a safe umask:
```
sudo su -
umask 077
```
Update your package repositories:
Debian
```
apt update
```
CentOS
```
yum update -y
```

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

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

Install the SendGrid Node.js client:
```
npm install sendgrid
```

Clone the sample repository:

git clone https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git

Go to the directory that contains the SendGrid sample:
```
cd nodejs-docs-samples/compute
```
Copy the sendgrid.js file:
```
cp sendgrid.js sendmail.js
```

Open sendmail.js for editing.

Replace your-sendgrid-api-key with the API key for your SendGrid account.
Replace [email protected] with the email address that you want to send mail from.
Replace [email protected] 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: '[email protected]',
    from: '[email protected]',
    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();

Run the program to send an email message through SendGrid:
```
node sendmail.js
```

Sending mail from an Exchange edge transport server

You can set up Microsoft Exchange to send outbound email with SendGrid by configuring an outbound send connector. For details, see Deploying Microsoft Exchange Server 2016 on Compute Engine.

Clean up

To avoid incurring charges to your Google Cloud account for the resources used in this tutorial, either delete the project that contains the resources, or keep the project and delete the individual resources.

Delete the project

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

To delete the project:

In the Google Cloud console, go to the Manage resources page.
Go to Manage resources
In the project list, select the project that you want to delete, and then click Delete.
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:

In the Google Cloud console, go to the VM instances page.
Go to VM instances
Select the checkbox for your sendgrid-tutorial instance.
To delete the instance, click More actions, click Delete, and then follow the instructions.

What's next

Explore reference architectures, diagrams, and best practices about Google Cloud. Take a look at our Cloud Architecture Center.