电子邮件不是由我们的应用程序发送的线程组织的

Question

Our website sends out a bunch of different emails mostly through PHP. They used to be grouped/threaded in email programs and now they are not which it is my understanding nothing has changed. Below is two emails that should have been grouped because they contain the same In-Reply-To but they are not inside of Outlook or on the iPhone. Both emails show

In-Reply-To: <[e-mail]>

which has always grouped them before. Can anyone see why these emails are not being grouped?

Email 1

Delivered-To: [e-mail]
Received: by 10.103.11.6 with SMTP id 6csp307367vsl;
        Fri, 10 Mar 2017 19:24:02 -0800 (PST)
X-Received: by 10.36.103.142 with SMTP id u136mr2057971itc.89.1489202642703;
        Fri, 10 Mar 2017 19:24:02 -0800 (PST)
Return-Path: <[e-mail]>
Received: from mail-io0-x235.google.com (mail-io0-x235.google.com. [2607:f8b0:4001:c06::235])
        by mx.google.com with ESMTPS id n199si1326906itb.8.2017.03.10.19.24.02
        for <[e-mail]>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Fri, 10 Mar 2017 19:24:02 -0800 (PST)
Received-SPF: pass (google.com: domain of [e-mail] designates 2607:f8b0:4001:c06::235 as permitted sender) client-ip=2607:f8b0:4001:c06::235;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@ourdomain-com.20150623.gappssmtp.com;
       spf=pass (google.com: domain of [e-mail] designates 2607:f8b0:4001:c06::235 as permitted sender) smtp.mailfrom=[e-mail]
Received: by mail-io0-x235.google.com with SMTP id z13so59783095iof.2
        for <[e-mail]>; Fri, 10 Mar 2017 19:24:02 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=ourdomain-com.20150623.gappssmtp.com; s=20150623;
        h=message-id:date:from:mime-version:subject:in-reply-to:cc:to;
        bh=98a6YBog7O8FgvzYhj8VEddAQRq3sc1wyTnyjOGytnY=;
        b=joBOm9WHQ+UVRKvPMm7F5Ea+hM4ZWn/3Mood/RQjp4hQf2VNvUWd+avZz0b2gK4O6v
         rqnCrFa7glFRp7U9l2DNI5aL0hyTJuBP2i3sd345TfTFQb24BiCtXsjCuHyZnmugPFLa
         osMixbC9rVv1wS2UEdnvlO9ReqIZ+C6yhKqd/Fj8zaIH7F/nluMlf83DpZMvhq53Ycjb
         bDGZiB5Swm2RMLnuthCaLlB97fQV1rcA4yn7koW9RMVSD54Ofm4Bore+U8K4cI6Pg4ZP
         HkZKMBnkW2DHhuJ8/S4T9TXIfMH1vS5v0v8Xg8i0rrKl2b1oln1pFldfSy1zzOJMdSzG
         oFxg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20161025;
        h=x-gm-message-state:message-id:date:from:mime-version:subject
         :in-reply-to:cc:to;
        bh=98a6YBog7O8FgvzYhj8VEddAQRq3sc1wyTnyjOGytnY=;
        b=ruXyS4BldDI8hzP+PJmYphI7tzmjVN/Gvjs/PkBTQtll+GZy8T7vBMFYWOEm55uuO/
         jM+psjhvR3yxfHYG32MopumtXcXNGe4oG/AxjYMz6cRVKErl1jzgjtizdkrjQa851Zc5
         DuDQRVxI2EVntQc3p1xdF+Qkb2JJ3oV8uocuemp+RIC+lvNHwv11gAAMI1JbKhIt3/dg
         ow8YkIdeoPwcNSI/ykW6DoJmMsab1w4XE6UFOITxkcoECD4nFNraTs/I5s4W21zyCZCs
         KBqOoE5ephqYKYC1dThQHhjmuwpOTnQ09I1nFw0jTaMzfgWWs2TV5Ch6eMop8VQx2uRl
         lFHg==
X-Gm-Message-State: AMke39nvKGM8U4dZtokVOiaBoLdsSB7JPZ/KAL6XAzfE2VYRd0fABCm2wmsdMMZ917J5vP70
X-Received: by 10.107.131.156 with SMTP id n28mr22664031ioi.39.1489202642265;
        Fri, 10 Mar 2017 19:24:02 -0800 (PST)
Return-Path: <[e-mail]>
Received: from localhost (116.226.198.104.bc.googleusercontent.com. [104.198.226.116])
        by smtp.gmail.com with ESMTPSA id y21sm5237558ioi.0.2017.03.10.19.24.02
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Fri, 10 Mar 2017 19:24:02 -0800 (PST)
Message-ID: <[e-mail]>
Date: Fri, 10 Mar 2017 19:24:02 -0800 (PST)
From: "OurDomain.com" <[e-mail]>
X-Google-Original-From: "OurDomain.com" <[e-mail]>
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="=_a3d730346de879d36ef3d83fa85aa6fa"
Subject: OurDomain.com: Order Notification for Famous Dex Live in Concert
In-Reply-To: <[e-mail]>
Cc: <[e-mail]>
To: <[e-mail]>

Email 2

Delivered-To: [e-mail]
Received: by 10.103.11.6 with SMTP id 6csp307375vsl;
        Fri, 10 Mar 2017 19:24:04 -0800 (PST)
X-Received: by 10.36.62.132 with SMTP id s126mr2176363its.28.1489202644800;
        Fri, 10 Mar 2017 19:24:04 -0800 (PST)
Return-Path: <[e-mail]>
Received: from mail-io0-x230.google.com (mail-io0-x230.google.com. [2607:f8b0:4001:c06::230])
        by mx.google.com with ESMTPS id u125si1334621itg.1.2017.03.10.19.24.04
        for <[e-mail]>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Fri, 10 Mar 2017 19:24:04 -0800 (PST)
Received-SPF: pass (google.com: domain of [e-mail] designates 2607:f8b0:4001:c06::230 as permitted sender) client-ip=2607:f8b0:4001:c06::230;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@ourdomain-com.20150623.gappssmtp.com;
       spf=pass (google.com: domain of [e-mail] designates 2607:f8b0:4001:c06::230 as permitted sender) smtp.mailfrom=[e-mail]
Received: by mail-io0-x230.google.com with SMTP id z13so59783308iof.2
        for <[e-mail]>; Fri, 10 Mar 2017 19:24:04 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=ourdomain-com.20150623.gappssmtp.com; s=20150623;
        h=message-id:date:from:mime-version:subject:in-reply-to:cc:to;
        bh=4fbE2w1OHi/8ZvFqyHDZ13xw3OFX3AoRAx9mFhz8JUw=;
        b=bs6ZDtP1nbsPfTdVLF692JfIoezxJXn28jD3TnUwcabXh+885IoTAOHqs2pqI4gxlP
         xQSbvi1jRJTeAaZqa0jafFih+SYxu8EUUVEn96uWRh1FJU4RkZlIzkHy3z+bYH9Qqem6
         Ipt3NNWyHPYKqHATctdckCf6oGjIzszXCcTd0fuD2kpuVtXxyZb+pWsYX6RAjT/d+ON+
         mEtOHXF069PcZWk4e6dBCW+EL+Y2xZha6uN10Lj0Mr0XehqPaZxzwfg+5PpTqcncEQ7A
         vzjEgZ3fHY2JtpQaAV9hmGKBjLLGLvJ9+VFartTINmMFVOxgc4hKQZxim7AyTaAD57X8
         unOA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20161025;
        h=x-gm-message-state:message-id:date:from:mime-version:subject
         :in-reply-to:cc:to;
        bh=4fbE2w1OHi/8ZvFqyHDZ13xw3OFX3AoRAx9mFhz8JUw=;
        b=svm/uLtJCHMynPx+hoM84IANd+cn6T9DLmvJ7XmjZXun1A9dl8z3WNE1NkhE2bBWlI
         JCFmKTnwdlP5psky0unZRlB53OebWNPaWoWAdLLrclbOiUOnm5TriCUMwh0WmpHPX7bj
         xRSw5E7Es9rWn9kQsP9NpGDOii05WfcknDBvNW/IasZ521BPqa3hslYVgbeJRioBXsBE
         ws2NLNEu69w4fRYMxUplzmztg7ttKIaOm+n+JKDOSXfBs2IJrxpAE/xUrhi6ebthZQHL
         5+SzZno0MSPqfvlJApvR3gE/LDIh8oI6uhj3UIpH0raXpF3/ORcnwO3V0tDCTOktr95t
         b24Q==
X-Gm-Message-State: AMke39lLSX5mXqTGQpzjunprUWlgZDHOeJyLR/6myt+avTlQsfZ/nSWGMy9oMFXsfxEofg==
X-Received: by 10.107.37.12 with SMTP id l12mr18067611iol.159.1489202644476;
        Fri, 10 Mar 2017 19:24:04 -0800 (PST)
Return-Path: <[e-mail]>
Received: from localhost (116.226.198.104.bc.googleusercontent.com. [104.198.226.116])
        by smtp.gmail.com with ESMTPSA id s97sm5226849ioi.50.2017.03.10.19.24.04
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Fri, 10 Mar 2017 19:24:04 -0800 (PST)
Message-ID: <[e-mail]>
Date: Fri, 10 Mar 2017 19:24:04 -0800 (PST)
From: "OurDomain.com" <[e-mail]>
X-Google-Original-From: "OurDomain.com" <[e-mail]>
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="=_316d1e71935372135c22d7148ac225ee"
Subject: OurDomain.com: Order Notification for Famous Dex Live in Concert
In-Reply-To: <[e-mail]>
Cc: <[e-mail]>
To: <[e-mail]>