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…).
https://gist.github.com/richp10/2938dbd28300241d444f45eb5d1d364f
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.