The problem with disposable mail is that it gets blocked quite often. For example, I have a list with more than 3000 domains of disposable mail servers and you can’t register or comment with such a mail on saashub.com or libhunt.com
You can bring your own domain, so broad block-list based blocking like that doesn't work. Plus, you're not locked in to the service. It's your domain - when you want to use something other than Kopi - you just change your MX record.
I would like to take a look on it.
You can use something like this. https://github.com/FGRibreau/mailchecker