PHPMailer OAuth2
This module provides basic OAuth2 support for PHPMailer SMTP, currently supporting Azure authentication. It allows you to configure OAuth2 settings and obtain authentication tokens within Drupal to send emails securely.
Looking for new maintainer
See #3365216: PHPMailer OAuth2 Looking for new maintainer.
Overview and configuration
Provides basic OAuth2 support for PHPMailer SMTP.
It currently only supports Azure authentication. Because Microsoft does not support client credentials flow for SMTP (yet), occasional manual updates of the auth and refresh token may be required.
Configuration is at: Config -> System -> PHPMailer OAuth2
Enter your settings and click "Save Configuration". Once it has been saved, click "Get auth token" to get new auth and refresh tokens.
Once enabled, set the Authentication Type within PHPMailer SMTP.
The redirect path to provide to Azure is /phpmailer_oauth2/aad-callback. For example:
https://www.example.com/phpmailer_oauth2/aad-callback
Install with composer.
composer require drupal/phpmailer_oauth2
Other providers
Review the code in the module to find out how it works so you can implement your own provider. This could be a stand-alone module or included within this module.
The PHPMailer library supports league/oauth2-client providers:
As of PHPMailer 6.6.0, the library now accepts anything that implements the OAuthProviderInterface. This includes Google's OAuth classes.
Alternatives
Gmail OAuth2 Client apparently uses OAuth2 Client and integrates with PHPMailer SMTP.
Many email services are recommending the use of their APIs instead of SMTP for sending email. The Pantheon hosting platform also recommends this approach.
There are a few modules for specific services.