Adding address validation

[jrmain]

I use SMTP Pro with Mailgun and it's working great. However, because we're getting so many spam registrations, I'd like to start using Mailgun's address validation feature.

I was wondering if you might consider allowing for a validation step in SMTP Pro. Or possibly provide some hints as to how it might be accomplished. Mailgun's documentation includes some examples.

Documentation: https://documentation.mailgun.com/en/latest/api-email-validation.html?highlight=validation#email-validation