Step 1: Install Post SMTP Plugin
Download and install Post SMTP from the (above) Github link or directly from the WordPress Dashboard.
Step 2: Activate Post SMTP Plugin
After installing and activating the plugin, you will see a message inviting you to start to configure the plugin. Click on Settings.
Step 3: Troubleshooting Screen
This is the main screen of WordPress Post SMTP plugin. To power the plugin, I have also introduced the troubleshooting screen on the right. It can be very handy in some situations.
Step 4: Start The Wizard
Click on “Start The Wizard” button, enter your email address and the name you want to appear in the email From field.
Step 5: Gmail SMTP Server
Within a few moments, the plugin will auto resolve the Gmail SMTP server. After that, click on the Next button.
Step 6: Run Connectivity Test
The wizard will run a Connectivity Test and after that, you will see the connection screen.
Step 7: Connect to Mail Server
The wizard will automatically recommend and select: SMTP-STARTTLS with OAuth 2.0 authentication to host smtp.gmail.com on port 587, click Next.
Step 8: Client ID and Client Secret
In the Authentication screen, you will need to input two parameters: Client ID and Client Secret.
Step 9: Gmail API in Google API Console
To get the Client ID and the Client Secret, visit Google API Console and log in to your Gmail Account if asked.
Select Create Project and then Continue.
Step 10: Google API Credentials
After a few seconds, the next screen will appear, select Go to credentials.
Step 11: Add Credentials to Project
Skip the current screen by clicking Client ID like the image below.
Step 12: Configure Consent Screen
In this step, you will need to name your project, press the button on the right.
Step 13: OAuth Consent Screen
Enter the Email address, fill product field and then Save.
Step 14: Create API Credentials
On the Create credentials drop-down, select OAuth client ID.
Step 15: Create Client ID
Select Web application, name your app and then copy the fields. I marked from the one with the same colors from the step number 8.
Step 16: Copy Client ID and Client Secret
Now, copy the Client ID and Client Secret from above and paste them in their respective fields on step number 8 and save.
Step 17: Grant permission with Google
Now from the page of Post SMTP under actions, select Grant permission with Google.
Step 18: Choose an Account
From the dialog box, select the Gmail account you want to use sending emails.
Step 19: Connet Post SMTP to Gmail
Approve the APP Name you used to send emails.
Step 20: Verify Post SMTP
To verify you configured everything correctly, just check that your status matches this one.
Step 21: Send a Test Email
The last step is to use Send a Test Email option to verify that everything is working as expected.
Step 22: Enter Destination Email
Enter the destination email, if everything is configured properly, you should get a report like this one.