Customs email headers and/or subjects tags

XioNoX · June 25, 2014, 8:24pm

Hi!

To be able to sort automatically notification emails sent by Discourse, it would be great if they could have customs headers (or a subject tag) based on the message’s content/content:

For example, here is a list of headers Bugzilla sends with each notification email:

X-Bugzilla-Reason: CC AssignedTo
X-Bugzilla-Type: dep_changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Classification: Other
X-Bugzilla-ID: 1014331
X-Bugzilla-Product: mozilla.org
X-Bugzilla-Component: Server Operations
X-Bugzilla-Version: other
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: foobar@email.com
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: FIXED
X-Bugzilla-Priority: –
X-Bugzilla-Assigned-To: email@email.com
X-Bugzilla-Target-Milestone: —
X-Bugzilla-Flags:
X-Bugzilla-OS: Linux
X-Bugzilla-Changed-Fields: Status Resolution
X-Bugzilla-Changed-Field-Names: bug_status resolution

Thanks!

downey · June 25, 2014, 8:55pm

lib/email/sender.rb

main


      
            if (optimized_1X&.filesize || upload.filesize) >
                 SiteSetting.secure_uploads_max_email_embed_image_size_kb.kilobytes
              return
            end
            true
          end
          
          #
          # Two behaviors in the mail gem collide:
          #
          #  1. Attachments are added as extra parts at the top level,
          #  2. When there are both text and html parts, the content type is set
          #     to 'multipart/alternative'.
          #
          # Since attachments aren't alternative renderings, for emails that contain
          # attachments and both html and text parts, some coercing is necessary.
          #
          # When there are alternative rendering and attachments, this method causes
          # the top level to be 'multipart/mixed' and puts the html and text parts
          # into a nested 'multipart/alternative' part.
          #

It’s called from:

github.com/discourse/discourse

lib/email/sender.rb

main


      
            # to the array of values for the header.
            @message.header[key] = nil
            @message.header[key] = our_value
          end
          
          value = header_value(key)
          
          # Remove Auto-Submitted header for group private message emails, it does
          # not make sense there and may hurt deliverability.
          #
          # From https://www.iana.org/assignments/auto-submitted-keywords/auto-submitted-keywords.xhtml:
          #
          # > Indicates that a message was generated by an automatic process, and is not a direct response to another message.
          @message.header[key] = nil if key.downcase == "auto-submitted" && smtp_group_id
          
          # Replace reply_key in custom headers or remove
          if value&.include?("%{reply_key}")
            # Delete old header first or else the same header will be added twice
            @message.header[key] = nil
            @message.header[key] = value.gsub!("%{reply_key}", reply_key) if reply_key.present?
          end

I’ll try to get some more details from the Discourse team about how the setting is intended to be used and what values could be substituted into custom headers.

mattdm · January 8, 2022, 4:31pm

@simon Compare

github.com/discourse/discourse

lib/email/message_builder.rb

c0d72ec3d


      
                # No point in adding a reply-to header if it is going to be identical
                # to the from address/alias. If the from option is not present, then
                # the default reply-to address is used.
                result['Reply-To'] = from_value if from_value != alias_email(@opts[:from])
              end
            end
          
            result.merge(MessageBuilder.custom_headers(SiteSetting.email_custom_headers))
          end
          
          def self.custom_headers(string)
            result = {}
            string.split('|').each { |item|
              header = item.split(':', 2)
              if header.length == 2
                name = header[0].strip
                value = header[1].strip
                result[name] = value if name.length > 0 && value.length > 0
              end
            } unless string.nil?
            result

to

github.com/discourse/discourse

lib/email/message_builder.rb

c0d72ec3d


      
                elsif SiteSetting.unsubscribe_via_email_footer
                  "unsubscribe_link_and_mail"
                else
                  "unsubscribe_link"
                end
                @template_args[:unsubscribe_instructions] = I18n.t(unsubscribe_string, @template_args)
              end
            end
          end
          
          def subject
            if @opts[:template] &&
                TranslationOverride.exists?(locale: I18n.locale, translation_key: "#{@opts[:template]}.subject_template")
              augmented_template_args = @template_args.merge({
                site_name: @template_args[:email_prefix],
                optional_re: @opts[:add_re_to_subject] ? I18n.t('subject_re') : '',
                optional_pm: @opts[:private_reply] ? @template_args[:subject_pm] : '',
                optional_cat: @template_args[:show_category_in_subject] ? "[#{@template_args[:show_category_in_subject]}] " : '',
                optional_tags: @template_args[:show_tags_in_subject] ? "#{@template_args[:show_tags_in_subject]} " : '',
                topic_title: @template_args[:topic_title] ? @template_args[:topic_title] : '',
              })

There is some complexity with templates vs. the email_subject setting which I don’t completely understand — it looks like the latter isn’t used if there is is a template, but I’m not sure when there isn’t a template! But that aside, the basic thing is that if the function that built the custom headers used the same templating, this would work and the custom headers could have useful dynamic information.

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Customs email headers and/or subjects tags

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