added smtputf8 to header

app/controllers/application_controller.rb

@@ -1,7 +1,7 @@
 class ApplicationController < ActionController::Base
   include Pagy::Backend
 
-  prepend_before_action :convert_punycode_params
+  # prepend_before_action :convert_punycode_params
 
   helper_method :turbo_frame_request?
 
@@ -66,11 +66,11 @@ def clear_flash
     flash.clear if turbo_frame_request?
   end
 
-  def convert_punycode_params
-    return unless email = request.params.dig(:user, :email)
+  # def convert_punycode_params
+  #   return unless email = request.params.dig(:user, :email)
 
-    request.params[:user][:email] = email.split('@').map { |val| SimpleIDN.to_ascii(val) }.join('@')
-  end
+  #   request.params[:user][:email] = email.split('@').map { |val| SimpleIDN.to_ascii(val) }.join('@')
+  # end
 
   protected
 

app/mailers/application_mailer.rb

@@ -1,4 +1,12 @@
 class ApplicationMailer < ActionMailer::Base
+  before_action :add_smtputf8_header
+
   default from: Rails.application.config.customization['email_from_address']
   layout 'mailer'
+
+  private
+
+  def add_smtputf8_header
+    headers['SMTPUTF8'] = 'true'
+  end
 end