Adding configurable e-mail blacklist

app/models/user.rb

@@ -8,6 +8,7 @@ class User < ApplicationRecord
 
   validates :account, presence: true
   validates :locale, inclusion: I18n.available_locales.map(&:to_s), unless: 'locale.nil?'
+  validates :email, email: true
 
   scope :prolific, -> { joins('inner join statuses on statuses.account_id = users.account_id').select('users.*, count(statuses.id) as statuses_count').group('users.id').order('statuses_count desc') }
   scope :recent,   -> { order('id desc') }