FIX: improve support for handling emails coming from screened email addresses

app/assets/javascripts/admin/templates/email-rejected.hbs

@@ -28,9 +28,13 @@
                 {{avatar email.user imageSize="tiny"}}
                 {{email.from_address}}
               {{/link-to}}
+            {{else}}
+              {{#if email.from_address}}
+                <a href='mailto:{{unbound email.from_address}}'>{{email.from_address}}</a>
               {{else}}
                 &mdash;
               {{/if}}
+            {{/if}}
           </div>
         </td>
         <td class="addresses">

app/controllers/admin/email_templates_controller.rb

@@ -14,6 +14,7 @@ class Admin::EmailTemplatesController < Admin::AdminController
                      "system_messages.email_reject_post_error_specified", "system_messages.email_reject_user_not_found",
                      "system_messages.email_reject_reply_key", "system_messages.email_reject_topic_closed",
                      "system_messages.email_reject_topic_not_found", "system_messages.email_reject_trust_level",
+                     "system_messages.email_reject_screened_email",
                      "system_messages.pending_users_reminder", "system_messages.post_hidden",
                      "system_messages.restore_failed", "system_messages.restore_succeeded",
                      "system_messages.spam_post_blocked", "system_messages.too_many_spam_flags",

app/jobs/scheduled/poll_mailbox.rb

@@ -55,6 +55,7 @@ module Jobs
         when Email::Receiver::EmptyEmailError             then :email_reject_empty
         when Email::Receiver::NoBodyDetectedError         then :email_reject_empty
         when Email::Receiver::UserNotFoundError           then :email_reject_user_not_found
+        when Email::Receiver::ScreenedEmailError          then :email_reject_screened_email
         when Email::Receiver::AutoGeneratedEmailError     then :email_reject_auto_generated
         when Email::Receiver::InactiveUserError           then :email_reject_inactive_user
         when Email::Receiver::BlockedUserError            then :email_reject_blocked_user

app/models/user.rb

@@ -25,6 +25,7 @@ class User < ActiveRecord::Base
   has_many :user_badges, -> { where('user_badges.badge_id IN (SELECT id FROM badges WHERE enabled)') }, dependent: :destroy
   has_many :badges, through: :user_badges
   has_many :email_logs, dependent: :delete_all
+  has_many :incoming_emails, dependent: :delete_all
   has_many :post_timings
   has_many :topic_allowed_users, dependent: :destroy
   has_many :topics_allowed, through: :topic_allowed_users, source: :topic

config/locales/server.en.yml

@@ -66,6 +66,7 @@ en:
         topic_closed_error: "Happens when a reply came in but the related topic has been closed."
         bounced_email_report: "Email is a bounced email report."
         auto_generated_email_reply: "Email contains a reply to an auto generated email."
+        screened_email_error: "Happens when the sender's email address was already screened."
 
   errors: &errors
     format: ! '%{attribute} %{message}'
@@ -1857,6 +1858,13 @@ en:
 
         Your reply was sent from an unknown email address. Try sending from another email address, or contact a staff member.
 
+    email_reject_screened_email:
+      subject_template: "[%{site_name}] Email issue -- Blocked Email"
+      text_body_template: |
+        We're sorry, but your email message to %{destination} (titled %{former_title}) didn't work.
+
+        Your reply was sent from a blocked email address. Try sending from another email address, or contact a staff member.
+
     email_reject_inactive_user:
       subject_template: "[%{site_name}] Email issue -- Inactive User"
       text_body_template: |

lib/email/receiver.rb

@@ -10,6 +10,7 @@ module Email
 
     class ProcessingError              < StandardError; end
     class EmptyEmailError              < ProcessingError; end
+    class ScreenedEmailError           < ProcessingError; end
     class UserNotFoundError            < ProcessingError; end
     class AutoGeneratedEmailError      < ProcessingError; end
     class AutoGeneratedEmailReplyError < ProcessingError; end
@@ -55,6 +56,8 @@ module Email
     end
 
     def process_internal
+      raise ScreenedEmailError if ScreenedEmail.should_block?(@from_email)
+
       user = find_or_create_user(@from_email, @from_display_name)
 
       raise UserNotFoundError if user.nil?
@@ -209,17 +212,21 @@ module Email
       user = nil
 
       User.transaction do
+        begin
           user = User.find_by_email(email)
 
           if user.nil? && SiteSetting.enable_staged_users
             username = UserNameSuggester.sanitize_username(display_name) if display_name.present?
-          user = User.create(
+            user = User.create!(
               email: email,
               username: UserNameSuggester.suggest(username.presence || email),
               name: display_name.presence || User.suggest_name(email),
               staged: true
             )
           end
+        rescue
+          user = nil
+        end
       end
 
       user

spec/components/email/receiver_spec.rb

@@ -17,7 +17,12 @@ describe Email::Receiver do
     expect { Email::Receiver.new("") }.to raise_error(Email::Receiver::EmptyEmailError)
   end
 
-  it "raises and UserNotFoundError when staged users are disabled" do
+  it "raises a ScreenedEmailError when email address is screened" do
+    ScreenedEmail.expects(:should_block?).with("screened@mail.com").returns(true)
+    expect { process(:screened_email) }.to raise_error(Email::Receiver::ScreenedEmailError)
+  end
+
+  it "raises an UserNotFoundError when staged users are disabled" do
     SiteSetting.enable_staged_users = false
     expect { process(:user_not_found) }.to raise_error(Email::Receiver::UserNotFoundError)
   end

spec/fixtures/emails/screened_email.eml

@@ -0,0 +1,9 @@
+Return-Path: <screened@mail.com>
+From: Not Found <screened@mail.com>
+Date: Fri, 15 Jan 2016 00:12:43 +0100
+Message-ID: <51@foo.bar.mail>
+Mime-Version: 1.0
+Content-Type: text/plain
+Content-Transfer-Encoding: 7bit
+
+Email from a screened email address.