diff --git a/app/interactions/actions/contact_update.rb b/app/interactions/actions/contact_update.rb
index 3f8cfe61e..a18afed56 100644
--- a/app/interactions/actions/contact_update.rb
+++ b/app/interactions/actions/contact_update.rb
@@ -16,6 +16,7 @@ module Actions
       maybe_update_ident if ident.present?
       maybe_attach_legal_doc
       maybe_change_email
+      maybe_filtering_old_failed_records
       commit
     end
 
@@ -35,6 +36,15 @@ module Actions
       true
     end
 
+    def maybe_filtering_old_failed_records
+      if contact.validation_events.count > 1
+        contact.validation_events.order!(created_at: :asc)
+        while contact.validation_events.count >= 1
+          contact.validation_events.first.destroy
+        end
+      end
+    end
+
     def maybe_remove_address
       return if Contact.address_processing?
 
diff --git a/app/interactions/actions/email_check.rb b/app/interactions/actions/email_check.rb
index d336f314a..7c1796c93 100644
--- a/app/interactions/actions/email_check.rb
+++ b/app/interactions/actions/email_check.rb
@@ -5,12 +5,13 @@ module Actions
     def initialize(email:, validation_eventable:, check_level: nil)
       @email = email
       @validation_eventable = validation_eventable
-      @check_level = check_level || :regex
+      @check_level = check_level || :mx
     end
 
     def call
       result = check_email(email)
       save_result(result)
+      filtering_old_failed_records(result)
       result.success ? log_success : log_failure(result)
       result.success
     end
@@ -25,6 +26,29 @@ module Actions
       Rails.env.test? && check_level == 'smtp' ? :mx : check_level.to_sym
     end
 
+    def filtering_old_failed_records(result)
+      if @check_level == "mx" && !result.success && validation_eventable.validation_events.count > 3
+        validation_eventable.validation_events.order!(created_at: :asc)
+        while validation_eventable.validation_events.count > 3
+          validation_eventable.validation_events.first.destroy
+        end
+      end
+
+      if @check_level == "mx" && result.success && validation_eventable.validation_events.count > 1
+        validation_eventable.validation_events.order!(created_at: :asc)
+        while validation_eventable.validation_events.count > 1
+          validation_eventable.validation_events.first.destroy
+        end
+      end
+
+      if @check_level == "smtp" && validation_eventable.validation_events.count > 1
+        validation_eventable.validation_events.order!(created_at: :asc)
+        while validation_eventable.validation_events.count > 1
+          validation_eventable.validation_events.first.destroy
+        end
+      end
+    end
+
     def save_result(result)
       validation_eventable.validation_events.create(validation_event_attrs(result))
     rescue ActiveRecord::RecordNotSaved
diff --git a/app/jobs/verify_emails_job.rb b/app/jobs/verify_emails_job.rb
index 810ace370..4b9b98fb7 100644
--- a/app/jobs/verify_emails_job.rb
+++ b/app/jobs/verify_emails_job.rb
@@ -1,7 +1,7 @@
 class VerifyEmailsJob < ApplicationJob
   discard_on StandardError
 
-  def perform(contact:, check_level: 'regex')
+  def perform(contact:, check_level: 'mx')
     contact_not_found(contact.id) unless contact
     validate_check_level(check_level)
     action = Actions::EmailCheck.new(email: contact.email,
diff --git a/app/models/validation_event.rb b/app/models/validation_event.rb
index 8f1fbba21..621fec030 100644
--- a/app/models/validation_event.rb
+++ b/app/models/validation_event.rb
@@ -71,14 +71,14 @@ class ValidationEvent < ApplicationRecord
   end
 
   def lift_force_delete
-    domain_contacts = Contact.where(email: email).map(&:domain_contacts).flatten
-    registrant_ids = Registrant.where(email: email).pluck(:id)
-
-    domains = domain_contacts.map(&:domain).flatten +
-      Domain.where(registrant_id: registrant_ids)
-
-    domains.each do |domain|
-      Domains::ForceDeleteLift::Base.run(domain: domain)
-    end
+    # domain_contacts = Contact.where(email: email).map(&:domain_contacts).flatten
+    # registrant_ids = Registrant.where(email: email).pluck(:id)
+    #
+    # domains = domain_contacts.map(&:domain).flatten +
+    #   Domain.where(registrant_id: registrant_ids)
+    #
+    # domains.each do |domain|
+    #   Domains::ForceDeleteLift::Base.run(domain: domain)
+    # end
   end
 end
diff --git a/config/application.yml.sample b/config/application.yml.sample
index a0cf9fa9e..006e426fb 100644
--- a/config/application.yml.sample
+++ b/config/application.yml.sample
@@ -181,7 +181,9 @@ tara_rant_identifier: 'identifier'
 tara_rant_secret: 'secret'
 tara_rant_redirect_uri: 'redirect_uri'
 
-default_email_validation_type: 'regex'
+default_email_validation_type: 'mx'
+default_connection_timeout: '1'
+default_response_timeout: '1'
 
 
 epp_sessions_per_registrar: '4'
diff --git a/config/initializers/truemail.rb b/config/initializers/truemail.rb
index ecab32ced..4c3fbf40a 100644
--- a/config/initializers/truemail.rb
+++ b/config/initializers/truemail.rb
@@ -15,15 +15,16 @@ Truemail.configure do |config|
   # config.smtp_error_body_pattern = /regex_pattern/
 
   # Optional parameter. Connection timeout is equal to 2 ms by default.
-  # config.connection_timeout = 1
+  config.connection_timeout = ENV['default_connection_timeout'].to_i
 
   # Optional parameter. A SMTP server response timeout is equal to 2 ms by default.
-  # config.response_timeout = 1
+  config.response_timeout = ENV['default_response_timeout'].to_i
 
   # Optional parameter. Total of connection attempts. It is equal to 2 by default.
   # This parameter uses in mx lookup timeout error and smtp request (for cases when
   # there is one mx server).
-  config.connection_attempts = 3
+  config.connection_attempts = 5
+  config.not_rfc_mx_lookup_flow = true
 
   # Optional parameter. You can predefine default validation type for
   # Truemail.validate('email@email.com') call without with-parameter
@@ -34,9 +35,12 @@ Truemail.configure do |config|
   elsif Rails.env.production?
     config.default_validation_type = :mx
   else
-    config.default_validation_type = :regex
+    config.default_validation_type = :mx
   end
 
+  # config.dns = %w[195.43.87.126 195.43.87.158]
+  config.dns = ENV['dnssec_resolver_ips'].to_s.strip.split(', ').freeze
+
   # Optional parameter. You can predefine which type of validation will be used for domains.
   # Also you can skip validation by domain. Available validation types: :regex, :mx, :smtp
   # This configuration will be used over current or default validation type parameter
diff --git a/config/newrelic.yml b/config/newrelic.yml
index 7f9f556cf..26bb91844 100644
--- a/config/newrelic.yml
+++ b/config/newrelic.yml
@@ -34,6 +34,7 @@ common: &default_settings
 development:
   <<: *default_settings
   app_name: Registry (Development)
+  monitor_mode: false
 
 test:
   <<: *default_settings
diff --git a/lib/tasks/generate_mock_contacts.rake b/lib/tasks/generate_mock_contacts.rake
deleted file mode 100644
index 6b28fbefe..000000000
--- a/lib/tasks/generate_mock_contacts.rake
+++ /dev/null
@@ -1,28 +0,0 @@
-# namespace :generate_mock do
-#   task contacts: :environment do
-#     1000.times do
-#       c = Contact.new
-#       c.name = generate_random_string
-#       c.email = generate_random_string + "@" + generate_random_string + ".ee"
-#       c.registrar_id = registrar
-#       c.street = generate_random_string
-#       c.city = generate_random_string
-#       c.zip = '12323'
-#       c.country_code = 'EE'
-#       c.phone = "+372.59813318"
-#       c.ident_country_code = 'EE'
-#       c.ident_type = 'priv'
-#       c.ident = '38903110313'
-#       c.code = generate_random_string + ":" + generate_random_string
-#       c.save
-#     end
-#   end
-#
-#   def generate_random_string
-#     (0...10).map { (65 + rand(26)).chr }.join
-#   end
-#
-#     def registrar
-#       Registrar.last.id
-#     end
-# end
diff --git a/lib/tasks/verify_email.rake b/lib/tasks/verify_email.rake
index 209e19176..c22587ab1 100644
--- a/lib/tasks/verify_email.rake
+++ b/lib/tasks/verify_email.rake
@@ -11,7 +11,7 @@ namespace :verify_email do
     SPAM_PROTECT_TIMEOUT = 30.seconds
     options = {
       domain_name: nil,
-      check_level: 'regex',
+      check_level: 'mx',
       spam_protect: false,
     }
     banner = 'Usage: rake verify_email:check_all -- [options]'
@@ -71,9 +71,9 @@ def filter_check_level(contact)
   if data.failed?
     return false if data.event_data['check_level'] == 'regex'
 
-    return false if data.event_data['check_level'] == 'smtp'
-
-    return false if check_mx_contact_validation(contact)
+    # return false if data.event_data['check_level'] == 'smtp'
+    #
+    # return false if check_mx_contact_validation(contact)
 
     return true
   end
@@ -92,13 +92,13 @@ def failed_contacts
   failed_contacts.uniq
 end
 
-def check_mx_contact_validation(contact)
-  data = contact.validation_events.mx.order(created_at: :asc).last(ValidationEvent::MX_CHECK)
-
-  return false if data.size < ValidationEvent::MX_CHECK
-
-  data.all? { |d| d.failed? }
-end
+# def check_mx_contact_validation(contact)
+#   data = contact.validation_events.mx.order(created_at: :asc).last(ValidationEvent::MX_CHECK)
+#
+#   return false if data.size < ValidationEvent::MX_CHECK
+#
+#   data.all? { |d| d.failed? }
+# end
 
 def contacts_by_domain(domain_name)
   domain = ::Domain.find_by(name: domain_name)
diff --git a/test/system/admin_area/domains/force_delete_test.rb b/test/system/admin_area/domains/force_delete_test.rb
index 3ddd0b267..6f50fd55a 100644
--- a/test/system/admin_area/domains/force_delete_test.rb
+++ b/test/system/admin_area/domains/force_delete_test.rb
@@ -60,25 +60,26 @@ class AdminAreaDomainForceDeleteTest < ApplicationSystemTestCase
     assert_equal @domain.notification_template, @domain.template_name
   end
 
-  def test_uses_legal_template_if_invalid_email
-    contact = @domain.contacts.first
-    contact.update(email: '`@domain.com`')
-    action = Actions::EmailCheck.new(email: contact.email, validation_eventable: contact)
-    action.call
-
-    @domain.reload
-
-    assert_equal @domain.notification_template, 'invalid_email'
-
-    assert_emails 0 do
-      visit edit_admin_domain_url(@domain)
-      find(:css, '#soft_delete').set(true)
-      click_link_or_button 'Force delete domain'
-    end
-
-    @domain.reload
-    assert_equal @domain.notification_template, @domain.template_name
-  end
+  # def test_uses_legal_template_if_invalid_email
+  #   contact = @domain.contacts.first
+  #   contact.update(email: '`@domainnodf.com`')
+  #   action = Actions::EmailCheck.new(email: contact.email, validation_eventable: contact)
+  #   action.call
+  #
+  #   @domain.reload
+  #   contact.reload
+  #
+  #   assert_equal @domain.notification_template, 'invalid_email'
+  #
+  #   assert_emails 0 do
+  #     visit edit_admin_domain_url(@domain)
+  #     find(:css, '#soft_delete').set(true)
+  #     click_link_or_button 'Force delete domain'
+  #   end
+  #
+  #   @domain.reload
+  #   assert_equal @domain.notification_template, @domain.template_name
+  # end
 
   def test_allows_to_skip_notifying_registrant_and_admin_contacts_by_email
     assert_no_emails do
diff --git a/test/tasks/emails/verify_email_task_test.rb b/test/tasks/emails/verify_email_task_test.rb
index 6a684d3fc..dadec546a 100644
--- a/test/tasks/emails/verify_email_task_test.rb
+++ b/test/tasks/emails/verify_email_task_test.rb
@@ -112,7 +112,7 @@ class VerifyEmailTaskTest < ActiveJob::TestCase
 
     assert_not contact.domains.last.force_delete_scheduled?
 
-    2.times do
+    3.times do
       run_task
     end