Emails are not threaded in Outlook 2013

[rumpelsepp]

What you describe is impossible – I don’t know how to get, in Ruby code, the message ID header that the mail server appends to emails at the time it sends them, before dispatching the email. That ID doesn’t even exist until the message is being transmitted.

Those ids are created at the time the message is sent by the mail server as far as I know, and they are internal to the mail server software.

As far as I know it is created by the first SMTP server when it is missing. Maybe this could help; it should be possible with action mailer.

• http://stackoverflow.com/a/6602846
• http://blog.mailgun.com/tips-tricks-avoiding-gmail-spam-filtering-when-using-ruby-on-rails-action-mailer/

Also, the “in reply to” should always be in reply to the original topic creation, the first post of the topic, which you may never have even received an notification about. So there is no “message id” to work with in that case…

That is not that bad. I just tried it on a mailman mailinglist in my inbox. I deleted the parent message and the threading did not break because the References headers are fine. Maybe also this commit description here could help a bit: https://projects.archlinux.org/aur.git/commit/?id=8658bf22aac73ed8d32d3f998c3c13528f415ffe

see here:

   Note: Some implementations parse the "References:" field to display
   the "thread of the discussion".  These implementations assume that
   each new message is a reply to a single parent and hence that they
   can walk backwards through the "References:" field to find the parent
   of each message listed there.