I take a robust approach to blocking disposable email addresses - after a bit of searching on the subject compiled a list of 3,700 domains to block. I use SSO so this is not managed within Discourse itself (not sure whether you could add this many records to the Discourse blacklist..).
Not entirely sure whether this is comprehensive or whether it includes ‘false positives’ - but in principle I am happy to try and prevent registrations from disposable email addresses.