Revert "Remove custom self.deliver_mail" (#11420)

Author: sampoder

app/mailers/application_mailer.rb

@@ -10,6 +10,16 @@ class ApplicationMailer < ActionMailer::Base
   # allow usage of application helper
   helper :application
 
+  def self.deliver_mail(mail)
+    # Our SMTP service will throw an error if we attempt
+    # to deliver an email without recipients. Occasionally
+    # that happens due to events without members. This
+    # will prevent those attempts from being made.
+    return if mail.recipients.compact.empty?
+
+    super(mail)
+  end
+
   protected
 
   def hcb_email_with_name_of(object)