An Organization cannot have a certain set of common email domains added to email_allowed_domains. The following email domains are not allowed:

gmail, aol, yahoo, icloud, hotmail, msn, comcast, live, outlook, att, earthlink, me, mac, sbcglobal, verizon, ig, mail, hey, laposte, wanadoo, googlemail, orange, rediffmail, uol, bol, free, gmx, yandex, ymail, libero