In-Reply-To email header is incorrect

To properly thread issue/MR discussion emails, they should correctly use the In-Reply-To header.

For example, here are consecutive 2 mails from #35430 (moved). (stripped some unrelated headers)

First one: https://gitlab.com/gitlab-org/gitlab-ce/issues/35430#note_35743098

Sender: gitlab@mg.gitlab.com
Date: Mon, 24 Jul 2017 10:43:49 +0000
From: Sean McGivern <gitlab@mg.gitlab.com>
Reply-To: "GitLab.org / GitLab Community Edition" <incoming+07d5996ab6e57a0bce96671a71c347b3@gitlab.com>
To: xxx@xxx.xxx
Message-ID: <30baf0e36b11a743b36f1e01f1664922@gitlab.com>
In-Reply-To: <issue_6187657@gitlab.com>
References: <issue_6187657@gitlab.com> <reply-07d5996ab6e57a0bce96671a71c347b3@gitlab.com>
Subject: Re: GitLab Community Edition | Freeze or remove V3 entities/endpoints (#35430)
X-GitLab-Project: GitLab Community Edition
X-GitLab-Project-Id: 13083
X-GitLab-Project-Path: gitlab-org/gitlab-ce
List-Unsubscribe: <https://gitlab.com/sent_notifications/REDACTED/unsubscribe?force=true>,<mailto:incoming+07d5996ab6e57a0bce96671a71c347b3+unsubscribe@gitlab.com>
X-GitLab-Issue-ID: 6187657
X-GitLab-Reply-Key: 07d5996ab6e57a0bce96671a71c347b3

I agree, copying is the safest for now. Good catch!

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Reply to this email directly or view it on GitLab: https://gitlab.com/gitlab-org/gitlab-ce/issues/35430#note_35743098
You're receiving this email because of your account on gitlab.com.

Second one: https://gitlab.com/gitlab-org/gitlab-ce/issues/35430#note_35799559

Sender: gitlab@mg.gitlab.com
Date: Mon, 24 Jul 2017 21:02:48 +0000
From: Oswaldo Ferreira <gitlab@mg.gitlab.com>
Reply-To: "GitLab.org / GitLab Community Edition" <incoming+fba7e22047a100bad9e3bb6a01b7e77c@gitlab.com>
To: xxx@xxx.xxx
Message-ID: <8d68b0e214605db0cdf162680081697b@gitlab.com>
In-Reply-To: <issue_6187657@gitlab.com>
References: <issue_6187657@gitlab.com> <reply-fba7e22047a100bad9e3bb6a01b7e77c@gitlab.com>
Subject: Re: GitLab Community Edition | Freeze or remove V3 entities/endpoints (#35430)
X-GitLab-Project: GitLab Community Edition
X-GitLab-Project-Id: 13083
X-GitLab-Project-Path: gitlab-org/gitlab-ce
List-Unsubscribe: <https://gitlab.com/sent_notifications/REDACTED/unsubscribe?force=true>,<mailto:incoming+fba7e22047a100bad9e3bb6a01b7e77c+unsubscribe@gitlab.com>
X-GitLab-Issue-ID: 6187657
X-GitLab-Reply-Key: fba7e22047a100bad9e3bb6a01b7e77c

Agree, thanks!

---
Reply to this email directly or view it on GitLab: https://gitlab.com/gitlab-org/gitlab-ce/issues/35430#note_35799559
You're receiving this email because of your account on gitlab.com.

Now, to properly thread conversations the second mail should use In-Reply-To: <30baf0e36b11a743b36f1e01f1664922@gitlab.com> in the header, because that's the Message-ID.

This is particularly useful when there are several parallel discussions in an issue/MR.

cc @reprazent

Reply by email was introduced in !1173 (merged) (closed #1360 (closed)) and some changes where made in !1480 (merged) (closed #2867 (closed)).

mentioned in issue #36239

mentioned in merge request !14289

assigned to @to1ne

mentioned in commit nolith/gitlab-ce@97f2b5f6

mentioned in commit maxraab/gitlab-ce@2acf3a56

mentioned in commit maxraab/gitlab-ce@f55aaca5

mentioned in merge request !14785