I recommend using this plugin: https://community.mybb.com/mods.php?acti...w&pid=1239
He has many more blocked domains and updates the plugin frequently.

MyBB Disposable Email Blacklist

MyBB Plugin which blocks over 1000 known anonymous, disposable, or spam email providers or services.

Originally created by Depressurize, I have added nearly twice as many blocked email providers.

Github Link: https://github.com/stardust342/mybb-disp...-blacklist

Original Plugin Link: http://community.mybb.com/mods.php?action=view&pid=293

Installing

1) Merge the inc folder with the one on your MyBB Webserver.

2) Activate it from your Plugin Configuration page of your MyBB Website.

Uninstalling

Deactivate it from your Plugin Configuration page of your MyBB Website.