I have noticed a number of member signups from disposable email service providers, including:
and on and on
Some are easy to spot based on their names, others not.
I have created two labels for accounts when I run across them so I can keep a lookout for behavior in the Mailgun and Cove dashboards.
It occurs to me that it might be interesting to develop a community-sourced “blacklist” for known disposable email address providers and a module that would flag new member signups with the label “Disposable” so ghost admins can keep on top of them. Maybe the list could be hosted on github and the module could check github for updates.