Mail Verify

This module will override the default mail_validator service with a hardened implementation that actually tries to connect to the client e-mail server to verify that the address does exist.

To run this module you will need to have access to an open port 25 and fsockopen(). The module will automatically check the availability of these every 24 hours and disable itself by defaulting to the original mail validation service implementation.

You should NOT use this module as a first stand protection against spam because you risk your IP address being graylisted by e-mail servers yielding this verification method useless (graylisted delivery attempts are treated as valid e-mails to prevent false positives).

Advantages of this module over other e-mail validation modules:

• Self shutdown when it detectes that the required connectivity to perform the validation is not available, defaults to Drupal's out-of-the-box default mail validator service
• Cache e-mail validation results
• Overrides the default mail validation system, so it requires no manual setup
• Setup your own validation services. Configure this module in one of your servers to centralize e-mail validation and caching.
• Writen from the ground up to leverage Drupal 8 services and good coding practices.