new alternative reply by email addresses

config/locales/server.en.yml

@@ -1171,6 +1171,7 @@ en:
 
     reply_by_email_enabled: "Enable replying to topics via email."
     reply_by_email_address: "Template for reply by email incoming email address, for example: %{reply_key}@reply.example.com or replies+%{reply_key}@example.com"
+    alternative_reply_by_email_addresses: "List of alternative templates for reply by email incoming email addresses."
     incoming_email_prefer_html: "Use the HTML instead of the text for incoming email. May cause unexcpeted formatting issues!"
 
     disable_emails: "Prevent Discourse from sending any kind of emails"
@@ -1363,6 +1364,7 @@ en:
       invalid_string_min: "Must be at least %{min} characters."
       invalid_string_max: "Must be no more than %{max} characters."
       invalid_reply_by_email_address: "Value must contain '%{reply_key}' and be different from the notification email."
+      invalid_alternative_reply_by_email_addresses: "All values must contain '%{reply_key}' and be different from the notification email."
       pop3_polling_host_is_empty: "You must set a 'pop3 polling host' before enabling POP3 polling."
       pop3_polling_username_is_empty: "You must set a 'pop3 polling username' before enabling POP3 polling."
       pop3_polling_password_is_empty: "You must set a 'pop3 polling password' before enabling POP3 polling."

config/site_settings.yml

@@ -534,7 +534,9 @@ email:
     validator: "ReplyByEmailEnabledValidator"
   reply_by_email_address:
     default: ''
-    validator: "ReplyByEmailAddressValidator"
+    validator: "AlternativeReplyByEmailAddressesValidator"
+  alternative_reply_by_email_addresses:
+    default: ''
   manual_polling_enabled:
     default: false
   pop3_polling_enabled:

lib/email/receiver.rb

@@ -327,15 +327,26 @@ module Email
 
       # reply
       match = reply_by_email_address_regex.match(address)
-      if match && match[1].present?
-        email_log = EmailLog.for(match[1])
+      if match && match.captures
+        match.captures.each do |c|
+          next if c.blank?
+          email_log = EmailLog.for(c)
           return { type: :reply, obj: email_log } if email_log
         end
       end
+    end
 
     def reply_by_email_address_regex
-      @reply_by_email_address_regex ||= Regexp.new Regexp.escape(SiteSetting.reply_by_email_address)
-                                                         .gsub(Regexp.escape("%{reply_key}"), "([[:xdigit:]]{32})")
+      @reply_by_email_address_regex ||= begin
+        reply_addresses = [
+           SiteSetting.reply_by_email_address,
+          *SiteSetting.alternative_reply_by_email_addresses.split("|")
+        ]
+        escaped_reply_addresses = reply_addresses.select { |a| a.present? }
+                                                 .map { |a| Regexp.escape(a) }
+                                                 .map { |a| a.gsub(Regexp.escape("%{reply_key}"), "([[:xdigit:]]{32})") }
+        Regexp.new(escaped_reply_addresses.join("|"))
+      end
     end
 
     def group_incoming_emails_regex

lib/validators/alternative_reply_by_email_addresses_validator.rb

@@ -0,0 +1,16 @@
+class AlternativeReplyByEmailAddressesValidator
+  def initialize(opts={})
+    @opts = opts
+  end
+
+  def valid_value?(val)
+    return true if val.blank?
+
+    validator = ReplyByEmailAddressValidator.new(@opts)
+    val.split("|").all? { |v| validator.valid_value?(v) }
+  end
+
+  def error_message
+    I18n.t('site_settings.errors.invalid_alternative_reply_by_email_addresses')
+  end
+end

lib/validators/reply_by_email_address_validator.rb

@@ -6,9 +6,9 @@ class ReplyByEmailAddressValidator
   def valid_value?(val)
     return true if val.blank?
 
-    !!(val =~ /@/i) &&
-    !!(val =~ /%{reply_key}/i) &&
-    val.gsub(/\+?%{reply_key}/i, "") != SiteSetting.notification_email
+    !!val["@"] &&
+    !!val["%{reply_key}"] &&
+    val.gsub(/\+?%{reply_key}/, "") != SiteSetting.notification_email
   end
 
   def error_message

spec/components/email/receiver_spec.rb

@@ -6,6 +6,7 @@ describe Email::Receiver do
   before do
     SiteSetting.email_in = true
     SiteSetting.reply_by_email_address = "reply+%{reply_key}@bar.com"
+    SiteSetting.alternative_reply_by_email_addresses = "alt+%{reply_key}@bar.com"
   end
 
   def process(email_name)

spec/fixtures/emails/html_reply.eml

@@ -1,6 +1,6 @@
 Return-Path: <discourse@bar.com>
 From: Foo Bar <discourse@bar.com>
-To: reply+4f97315cc828096c9cb34c6f1a0d6fe8@bar.com
+To: alt+4f97315cc828096c9cb34c6f1a0d6fe8@bar.com
 Date: Fri, 15 Jan 2016 00:12:43 +0100
 Message-ID: <18@foo.bar.mail>
 Mime-Version: 1.0