FIX: Parse address lists in embedded emails (#14514)

Same fix is applied to emails immediately after being parsed because
long headers are sometimes in an invalid format.

lib/email/receiver.rb

@@ -3,7 +3,6 @@
 require "digest"
 
 module Email
-
   class Receiver
     # If you add a new error, you need to
     #   * add it to Email::Processor#handle_failure()
@@ -72,8 +71,7 @@ module Email
           # do not create a new `IncomingEmail` record to avoid double ups.
           return if @incoming_email = find_existing_and_update_imap
 
-          ensure_valid_address_lists
-          ensure_valid_date
+          Email::Validator.ensure_valid!(@mail)
 
           @from_email, @from_display_name = parse_from_field
           @from_user = User.find_by_email(@from_email)
@@ -121,22 +119,6 @@ module Email
       incoming_email
     end
 
-    def ensure_valid_address_lists
-      [:to, :cc, :bcc].each do |field|
-        addresses = @mail[field]
-
-        if addresses&.errors.present?
-          @mail[field] = addresses.to_s.scan(/\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b/i)
-        end
-      end
-    end
-
-    def ensure_valid_date
-      if @mail.date.nil?
-        raise InvalidPost, I18n.t("system_messages.email_reject_invalid_post_specified.date_invalid")
-      end
-    end
-
     def is_blocked?
       return false if SiteSetting.ignore_by_title.blank?
       Regexp.new(SiteSetting.ignore_by_title, Regexp::IGNORECASE) =~ @mail.subject
@@ -915,7 +897,13 @@ module Email
     end
 
     def embedded_email
-      @embedded_email ||= embedded_email_raw.present? ? Mail.new(embedded_email_raw) : nil
+      @embedded_email ||= if embedded_email_raw.present?
+        mail = Mail.new(embedded_email_raw)
+        Email::Validator.ensure_valid_address_lists!(mail)
+        mail
+      else
+        nil
+      end
     end
 
     def process_forwarded_email(destination, user)

lib/email/validator.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module Email
+  class Validator
+    def self.ensure_valid!(mail)
+      Email::Validator.ensure_valid_address_lists!(mail)
+      Email::Validator.ensure_valid_date!(mail)
+
+      mail
+    end
+
+    def self.ensure_valid_address_lists!(mail)
+      [:to, :cc, :bcc].each do |field|
+        addresses = mail[field]
+
+        if addresses&.errors.present?
+          mail[field] = addresses.to_s.scan(/\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b/i)
+        end
+      end
+    end
+
+    def self.ensure_valid_date!(mail)
+      if mail.date.nil?
+        raise Email::Receiver::InvalidPost, I18n.t("system_messages.email_reject_invalid_post_specified.date_invalid")
+      end
+    end
+  end
+end