The goal of our
ActivationMailFormMixin is to send an account activation email to a new user. To that end, we must provide the string for an error in the form in the event the email is not sent. In Example 21.31, we create a
mail_validation_error attribute for subclasses of the mixin to override, allowing developers to specify the output of the error in their own class.
23 class ActivationMailFormMixin: 24 mail_validation_error = ''
While we use parts of the form’s validation system to inform Django whether email was sent or not, we also want to be able to check this on the go. We therefore create a