Checking whether Email Address exists in external database

[sacom (Samuel Aguilera (Gravity Forms))]

You can use the gform_field_validation filter to check the email entered using your own custom PHP code. There’s an example in this filter documentation that you could use as base for your code: https://docs.gravityforms.com/gform_field_validation/#h-11-email-validation-by-third-party-api