In any case, I finally decided to register using a throwaway spambox from Gmail instead of Mailinator (what difference does it make, really...) and it turns out the Laravel Factory is inferior to Voyager as it doesn't support roles out of the box. Which is a pity as other things have been solved quite nicely. I'll give it a try in a few months, maybe they catch up.
In our case we block all free and disposable email address since nobody without a corporate or university email address uses our service (it is aimed at scientists).
We used to let anyone use the service for free without registering for small scale use, but what we found were some commercial suppliers (our target market) were just telling their customers to use our free service rather than fork out the $0.02 it would have cost them to buy a license on assays they were selling for $10. Once cutoff from the ability to freeload, quite a number of these commercial suppliers decided to buy a license from us.
The good thing about this is not only did we get the business, but their customers got the benefit of our service automatically.
The funny thing is apart from emailing the free code we almost never contact anyone since we know 99% of our free users are not potential paying customers and so there is no point wasting our time on them. We only know this because they give us their real email address which allows us to screen them out.