FIX: invalid html in notification emails when template has been customized

app/mailers/user_notifications.rb

@@ -252,12 +252,10 @@ class UserNotifications < ActionMailer::Base
   end
 
   def email_post_markdown(post, add_posted_by=false)
-    result = "[email-indent]\n"
-    result << "#{post.raw}\n\n"
+    result = "#{post.raw}\n\n"
     if add_posted_by
       result << "#{I18n.t('user_notifications.posted_by', username: post.username, post_date: post.created_at.strftime("%m/%d/%Y"))}\n\n"
     end
-    result << "[/email-indent]\n"
     result
   end
 

lib/email/sender.rb

@@ -51,8 +51,6 @@ module Email
         end
       end
 
-      @message.parts[0].body = @message.parts[0].body.to_s.gsub(/\[\/?email-indent\]/, '')
-
       # Fix relative (ie upload) HTML links in markdown which do not work well in plain text emails.
       # These are the links we add when a user uploads a file or image.
       # Ideally we would parse general markdown into plain text, but that is almost an intractable problem.

lib/email/styles.rb

@@ -186,10 +186,7 @@ module Email
     def to_html
       strip_classes_and_ids
       replace_relative_urls
-      @fragment.to_html.tap do |result|
-        result.gsub!(/\[email-indent\]/, "<div style='margin-left: 15px'>")
-        result.gsub!(/\[\/email-indent\]/, "</div>")
-      end
+      @fragment.to_html
     end
 
     def strip_avatars_and_emojis