Not entirely sure if you can do that with the built-in email validation rule. A simple dirty way would be to do a simple if-check and skip email validation if the input email is one of your selected emails.

true, this could be a neat and simple solution. But how do I implement that solution while using form-request-validation?

I would guess you have to extend the validator and create a custom unique rule that accepts exceptions in string format. Read up on extending the validator and check out the validateUnique method in this file: https://github.com/laravel/framework/blob/5.0/src/Illuminate/Validation/Validator.php

You can use that as a base for your extension and just add what you need.

If you need just a couple objects (users) it's easier to create them manually in php artisan tinker console, than to write a custom validator with an exception.