Use the same email validation for User and Email

Otherwise, it is possible that a `User` primary email is successfully
saved, but it cannot be added to the emails table due to being invalid
for the `Email` model.

The `Email#email` validation is now more relaxed, and the same as the
`User#email` validation: it is the Devise email validation, that
only checks that there is a single @ sign separating local
part and domain. The previous stricter Email#email validation was
enforcing compliance with RFC3696, but many mail servers allow addresses
that are not fully compliant with the RFC. Therefore, the relaxed
validation is preferable, to avoid blocking working email addresses.

Changelog: fixed

app/models/email.rb

@@ -6,8 +6,8 @@ class Email < ApplicationRecord
 
   belongs_to :user, optional: false
 
-  validates :email, presence: true, uniqueness: true
-  validate :validate_email_format
+  validates :email, presence: true, uniqueness: true, devise_email: true
+
   validate :unique_email, if: ->(email) { email.email_changed? }
 
   scope :confirmed, -> { where.not(confirmed_at: nil) }
@@ -33,10 +33,6 @@ class Email < ApplicationRecord
     self.errors.add(:email, 'has already been taken') if primary_email_of_another_user?
   end
 
-  def validate_email_format
-    self.errors.add(:email, I18n.t(:invalid, scope: 'valid_email.validations.email')) unless ValidateEmail.valid?(self.email)
-  end
-
   # once email is confirmed, update the gpg signatures
   def update_invalid_gpg_signatures
     user.update_invalid_gpg_signatures if confirmed?

ee/spec/lib/ee/gitlab/usage_data_non_sql_metrics_spec.rb

@@ -16,7 +16,7 @@ RSpec.describe Gitlab::UsageDataNonSqlMetrics do
         described_class.uncached_data
       end
 
-      expect(recorder.count).to eq(63)
+      expect(recorder.count).to eq(65)
     end
   end
 end

spec/controllers/profiles/emails_controller_spec.rb

@@ -49,7 +49,7 @@ RSpec.describe Profiles::EmailsController do
     end
 
     context 'when email address is invalid' do
-      let(:email) { 'invalid.@example.com' }
+      let(:email) { 'invalid@@example.com' }
 
       it 'does not send an email confirmation' do
         expect { subject }.not_to change { ActionMailer::Base.deliveries.size }

spec/features/profiles/emails_spec.rb

@@ -44,7 +44,7 @@ RSpec.describe 'Profile > Emails' do
     end
 
     it 'does not add an invalid email' do
-      fill_in('Email', with: 'test.@example.com')
+      fill_in('Email', with: 'test@@example.com')
       click_button('Add email address')
 
       email = user.emails.find_by(email: email)

spec/models/email_spec.rb

@@ -10,7 +10,7 @@ RSpec.describe Email do
   end
 
   describe 'validations' do
-    it_behaves_like 'an object with RFC3696 compliant email-formatted attributes', :email do
+    it_behaves_like 'an object with email-formatted attributes', :email do
       subject { build(:email) }
     end
 

spec/models/user_spec.rb

@@ -436,7 +436,7 @@ RSpec.describe User do
       subject { build(:user) }
     end
 
-    it_behaves_like 'an object with RFC3696 compliant email-formatted attributes', :public_email, :notification_email do
+    it_behaves_like 'an object with email-formatted attributes', :public_email, :notification_email do
       subject { create(:user).tap { |user| user.emails << build(:email, email: email_value, confirmed_at: Time.current) } }
     end