FIX: Processing incoming email should be done in a background job.

app/controllers/admin/email_controller.rb

@@ -84,8 +84,8 @@ class Admin::EmailController < Admin::AdminController
 
   def handle_mail
     params.require(:email)
-    Email::Processor.process!(params[:email])
+    Jobs.enqueue(:process_email, mail: params[:email], retry_on_rate_limit: true)
-    render plain: "email was processed"
+    render plain: "email has been received and is queued for processing"
   end
 
   def raw_email

app/jobs/regular/process_email.rb

@@ -4,7 +4,7 @@ module Jobs
     sidekiq_options retry: 3
 
     def execute(args)
-      Email::Processor.process!(args[:mail], false)
+      Email::Processor.process!(args[:mail], args[:retry_on_rate_limit] || false)
     end
 
     sidekiq_retries_exhausted do |msg|

lib/email/receiver.rb

@@ -553,7 +553,7 @@ module Email
     def create_post_with_attachments(options={})
       # deal with attachments
       attachments.each do |attachment|
-        tmp = Tempfile.new("discourse-email-attachment")
+        tmp = Tempfile.new(["discourse-email-attachment", File.extname(attachment.filename)])
         begin
           # read attachment
           File.open(tmp.path, "w+b") { |f| f.write attachment.body.decoded }

spec/controllers/admin/email_controller_spec.rb

@@ -71,4 +71,16 @@ describe Admin::EmailController do
     end
   end
 
+  context '#handle_mail' do
+    before do
+      log_in_user(Fabricate(:admin))
+      SiteSetting.queue_jobs = true
+    end
+
+    it 'should enqueue the right job' do
+      expect { xhr :post, :handle_mail, email: email('cc') }
+        .to change { Jobs::ProcessEmail.jobs.count }.by(1)
+    end
+  end
+
 end

spec/controllers/email_controller_spec.rb

@@ -232,6 +232,4 @@ describe EmailController do
     end
   end
 
-
-
 end