Add Site Setting to use HTML from incoming email when available. (#4236)

config/locales/server.en.yml

@@ -1166,6 +1166,7 @@ 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"
+    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"
 

config/site_settings.yml

@@ -544,6 +544,8 @@ email:
   pop3_polling_username: ''
   pop3_polling_password: ''
   log_mail_processing_failures: false
+  incoming_email_prefer_html:
+    default: false
   email_in:
     default: false
     client: true

lib/email/receiver.rb

@@ -212,16 +212,21 @@ module Email
         text = fix_charset(@mail)
       end
 
-      # prefer text over html
-      text = trim_discourse_markers(text) if text.present?
-      text, elided = EmailReplyTrimmer.trim(text, true) if text.present?
-      return [text, elided] if text.present?
+      use_html = html.present? && (!text.present? || SiteSetting.incoming_email_prefer_html)
+      use_text = text.present? unless use_html
 
-      # clean the html if that's all we've got
-      html = Email::HtmlCleaner.new(html).output_html if html.present?
-      html = trim_discourse_markers(html) if html.present?
-      html, elided = EmailReplyTrimmer.trim(html, true) if html.present?
-      return [html, elided] if html.present?
+      if use_text
+        text = trim_discourse_markers(text)
+        text, elided = EmailReplyTrimmer.trim(text, true)
+        return [text, elided]
+      end
+
+      if use_html
+        html = Email::HtmlCleaner.new(html).output_html
+        html = trim_discourse_markers(html)
+        html, elided = EmailReplyTrimmer.trim(html, true)
+        return [html, elided]
+      end
     end
 
     def fix_charset(mail_part)

spec/components/email/receiver_spec.rb

@@ -171,6 +171,18 @@ describe Email::Receiver do
       expect(topic.posts.last.raw).to eq("This is the *text* part.")
     end
 
+    it "prefers html over text when site setting is enabled" do
+      SiteSetting.incoming_email_prefer_html = true
+      expect { process(:text_and_html_reply) }.to change { topic.posts.count }
+      expect(topic.posts.last.raw).to eq('This is the <b>html</b> part.')
+    end
+
+    it "uses text when prefer_html site setting is enabled but no html is available" do
+      SiteSetting.incoming_email_prefer_html = true
+      expect { process(:text_reply) }.to change { topic.posts.count }
+      expect(topic.posts.last.raw).to eq("This is a text reply :)")
+    end
+
     it "removes the 'on <date>, <contact> wrote' quoting line" do
       expect { process(:on_date_contact_wrote) }.to change { topic.posts.count }
       expect(topic.posts.last.raw).to eq("This is the actual reply.")