Move email checks and validation methods to concern

app/models/concerns/email_checkable.rb

@@ -0,0 +1,19 @@
+module Concerns
+  module EmailCheckable
+    extend ActiveSupport::Concern
+
+    def verify_email_mx_smtp(field:, email:)
+      errors.add(field, :invalid) unless email.blank? || Truemail.valid?(email)
+    end
+
+    def correct_email_format
+      verify_email_mx_smtp(field: :email, email: email)
+    end
+
+    def correct_billing_email_format
+      return if self[:billing_email].blank?
+
+      verify_email_mx_smtp(field: :billing_email, email: billing_email)
+    end
+  end
+end

app/models/registrar.rb

@@ -1,6 +1,7 @@
 class Registrar < ApplicationRecord
   include Versions # version/registrar_version.rb
   include Concerns::Registrar::BookKeeping
+  include Concerns::EmailCheckable
   include Concerns::Registrar::LegalDoc
 
   has_many :domains, dependent: :restrict_with_error
@@ -193,18 +194,4 @@ class Registrar < ApplicationRecord
   def vat_liable_in_foreign_country?
     !vat_liable_locally?
   end
-
-  def verify_email_mx_smtp(field:, email:)
-    errors.add(field, :invalid) unless email.blank? || Truemail.valid?(email)
-  end
-
-  def correct_email_format
-    verify_email_mx_smtp(field: :email, email: email)
-  end
-
-  def correct_billing_email_format
-    return if self[:billing_email].blank?
-
-    verify_email_mx_smtp(field: :billing_email, email: billing_email)
-  end
 end