Add disposable email validations

app/models/user.rb

@@ -95,7 +95,7 @@ class User < ApplicationRecord
   accepts_nested_attributes_for :invite_request, reject_if: ->(attributes) { attributes['text'].blank? && !Setting.require_invite_text }
   validates :invite_request, presence: true, on: :create, if: :invite_text_required?
 
-  validates :email, presence: true, email_address: true
+  validates :email, presence: true, email_address: true, disposable_email: true
 
   validates_with BlacklistedEmailValidator, if: -> { ENV['EMAIL_DOMAIN_LISTS_APPLY_AFTER_CONFIRMATION'] == 'true' || !confirmed? }
   validates_with EmailMxValidator, if: :validate_email_dns?

app/validators/disposable_email_validator.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+class DisposableEmailValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    return if value.blank?
+
+    return unless disposable_email?(value)
+
+    record.errors.add(
+      attribute,
+      (options[:message] || I18n.t('disposable_email_validator.invalid'))
+    )
+  end
+
+  private
+
+  def disposable_email?(email)
+    email_address = begin
+      Mail::Address.new(email.downcase)
+    rescue
+      nil
+    end
+
+    return false unless email_address
+
+    disposable_email_domains.include?(email_address.domain)
+  end
+
+  def disposable_email_domains
+    file_path = Rails.root.join('data', 'disposable_email_domains.txt')
+    return [] unless File.exist? file_path
+
+    data = File.read(file_path)
+    JSON.parse(data)
+  end
+end

config/locales/en.yml

@@ -1166,6 +1166,8 @@ en:
       more_details_html: For more details, see the <a href="%{terms_path}">privacy policy</a>.
       username_available: Your username will become available again
       username_unavailable: Your username will remain unavailable
+  disposable_email_validator:
+    invalid: from disposable domain is not allowed
   disputes:
     strikes:
       action_taken: Action taken

spec/validators/disposable_email_validator_spec.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe DisposableEmailValidator do
+  describe '#validate' do
+    it 'does not allow disposable email domains' do
+      user = Fabricate.build(:user, email: 'user@1994gmail.com')
+      expect(user).to_not be_valid
+      expect(user.errors.first.type).to eq I18n.t('disposable_email_validator.invalid')
+    end
+
+    it 'allows valid email domain' do
+      user = Fabricate.build(:user, email: 'user@gmail.com')
+      expect(user).to be_valid
+    end
+  end
+end