Emails forwarded to Service Desk email don't come in (when key in envelope-to header)

This is more or less an enhancement of #2247 (closed).

Additional to the already checked headers there is envelope-to which, as my googling skills lead me to, seems used for multiple german providers. See https://www.verbraucherzentrale.de/wissen/digitale-welt/phishingradar/so-lesen-sie-den-mailheader-6077 (German text).

Use case

I setup up support@foo.bar to forward mails to gitlab+myproject-@incoming.foo.bar to set up a small service desk. My mail provider 1&1 IONOS (https://www.ionos.de/) adds the service desk mail to an envelope-to header.

Mail example:

Return-Path: <max@winterstein.mx>
Received: from [217.72.192.67] ([217.72.192.67]) by mx.kundenserver.de
 (mxeue110 [217.72.192.67]) with ESMTPS (Nemesis) id 1MdMU2-1i0Y2E3ta4-00ZDyu
 for <gitlab+myproject-@incoming.foo.bar>; Tue, 26 Nov 2019 15:22:42
 +0100
Received: from smtprelay03.ispgateway.de ([80.67.29.28]) by mx.kundenserver.de
 (mxeue110 [217.72.192.67]) with ESMTPS (Nemesis) id 1MnIdG-1i8D023ejs-00jA9A
 for <support@foo.bar>; Tue, 26 Nov 2019 15:22:42 +0100
Received: from [10.240.177.4] (helo=EXFE04.EXCHANGE.INT)
	by smtprelay03.ispgateway.de with esmtps (TLSv1.2:ECDHE-RSA-AES256-SHA384:256)
	(Exim 4.92.3)
	(envelope-from <max@winterstein.mx>)
	id 1iZbjm-000441-5H
	for support@foo.bar; Tue, 26 Nov 2019 15:22:42 +0100
Received: from EXDAG29-1.EXCHANGE.INT (10.240.178.184) by
 EXDAG29-2.EXCHANGE.INT (10.240.178.185) with Microsoft SMTP Server (TLS) id
 15.0.1395.4; Tue, 26 Nov 2019 15:22:41 +0100
Received: from EXDAG29-1.EXCHANGE.INT ([10.240.179.57]) by
 EXDAG29-1.EXCHANGE.INT ([10.240.179.57]) with mapi id 15.00.1395.000; Tue, 26
 Nov 2019 15:22:41 +0100
From: "max@winterstein.mx" <max@winterstein.mx>
To: "support@foo.bar" <support@foo.bar>
Subject: test373
Thread-Topic: test373
Thread-Index: AQHVpGT2uiHl62aIf0OT/+w1gFu7uw==
Date: Tue, 26 Nov 2019 14:22:41 +0000
Message-ID: <7e2296f83dbf4de388cbf5f56f52c11f@EXDAG29-1.EXCHANGE.INT>
Accept-Language: de-DE, en-US
Content-Language: de-DE
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-ms-exchange-transport-fromentityheader: Hosted
x-originating-ip: [10.10.10.10]
Content-Type: multipart/alternative;
	boundary="_000_7e2296f83dbf4de388cbf5f56f52c11fEXDAG291EXCHANGEINT_"
MIME-Version: 1.0
Envelope-To: <gitlab+myproject-@incoming.foo.bar>
X-Spam-Flag: NO
X-UI-Filterresults: notjunk:1;V03:K0:rT/ntJHc7bk=:uI/HpEDkpjAJhvDklp81PXL+WS
 TuAPOocZl2+lctDH05RHD/JdrwWLOdDWBIoKUjy7oweTrclrOkjV6mF6UbcB+uijFPWJc0QoP
 nbZaKE5DFYhZiIWLtftfE74w3Inpa1myNtqrRnHWYNfodkfdWQsIg6C21VZezvBzGi1L5s6Ef
 hK5R3JwEOLoORzT6qgYRFnvqbRSku7O96dxN/Ea9GqgGbqxTZ73BlL8hKsmJJ4ExRrL05854A
 x1aearOcxlK1NUNKlTIgkiv+jYA+FWPWsAnmyIX1MtCYCeBvLVF/fXDvU6vKZ2+lrvT+XQZz+
 c4uvnMqXbu0R03s9ffzEJta5NRzt2NW6SjB9xYQ4BOOHAIptJlsM0lsfKWKSKjj2QmtFzgABa
 KFSlIgIWRzW6Q7qGKFxePqNYtHWHIBoCnMCu6WHUjVlKlA6d613UVXOj7o4bOR6totmD0Qswn
 tomAAoYr27bh34Xrl4EJAH4P3zqy6JrkH12/iLPJjBm2IUmzpLp2N5UtqAnH2QqCHtzkpsrip
 vbEvKApSR6SbBYKkb28/c5yhAPp57PMw3tGerPzXdMgMid14KgM5iwgDQGnkR9CFV6KtB53Fx
 e5BNf2DPeMZU1TlR8EJK3zQ7Ze9fFdvDX8EX/Y4quhmUY7T4TgzDidJSUGLntQOO49cxhC0y4
 tH52KRLOxA+qc3D36svvPdURLb9yBm4DJYqMU5FvcVYM4HHzoMlhY3CiIziejX1UcE8NqJBYu
 knWlxSmfUl9Z52X3swrkYZefflDs1n2zQ2dvBCj+yvSkzUP2ZhWq4LE5Z2JqzS1UoUza3B3Wk
 IclOSGA1DiSMro4QU5a9DJyjxj3EMDof7qY9jrnYlp91mkW/y7CauCpKw9I1JTNuAMlk5kiBY
 nNlewo0RGoVy3BL5QnXOMpGmr9yoZERfMhuJSp+bIlH6uiNgEhDXgA5l0bP+iFXxIhsnWhNf3
 0mfnthCn+i3LeaBY8B52Mqxuvtjzu90QphA3raN74fzaAidtxbIJshhZQDf0uANgkZJnOvqWm
 S1VkXDJL9qPvXBOqVEWhL5HLRxAS8NltASo7KaAdVSMX46zq7PA2omIERnJurcJ/lFeSgCJKS
 mvkGMmbtk2P85tnLQcP5zoT5iTrQylCewD5OYdQaYe6JJ4c6uMDeDng2++ELpcpfzrBYwoOuW
 nKLtX+ksf/Tm3ca4bg5Q4We95DOJj3CJ8AhZs4sRyNpZ+8J5MCl0PmV5Mdosq9RAtBko8vRu/
 DUeBwOlMS46GD0/Kt/yWnUmKdFjLzCJF9H2tzsKvKQ7OIWemaxd2Ua3riyyHp12Vsyx1fAk9+
 topAB05BLjEo/gTtLCvBXYK4XrMUukLjlHZ8mi2Nb6gFDUN8geSUkyV+WJ46R5OriWc0sdc7D
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 t+Qzpf5fLrXXDj53ZBcBirbl7guXHVFSUeD1QQmEhKgFpXYBzIpFIvfaTI55G+fJofrQRCQAb
 4Own1Oh2IAwScbIqGVadLrYwbU/arC6jPrOif+gSrFJmVTpQq9O2JIbVmeNyI/YsCumGMoBLC
 YIDwkokDXH9sh82J1vz97oh602WRKS+7wYr0wvcUqeCW58xanLlhOF+DY1lK+LElfh3G3hHzY
 A7X3qgXO34FrIDIIXT0AzjkOxn+mIG5V6Xstpi3G2NtBA==

--_000_7e2296f83dbf4de388cbf5f56f52c11fEXDAG291EXCHANGEINT_
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable



--_000_7e2296f83dbf4de388cbf5f56f52c11fEXDAG291EXCHANGEINT_
Content-Type: text/html; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Diso-8859-=
1">
<style type=3D"text/css" style=3D"display:none"><!--P{margin-top:0;margin-b=
ottom:0;} --></style>
</head>
<body dir=3D"ltr" style=3D"font-size:12pt;color:#000000;background-color:#F=
FFFFF;font-family:Calibri,Arial,Helvetica,sans-serif;">
<p><br>
</p>
</body>
</html>

--_000_7e2296f83dbf4de388cbf5f56f52c11fEXDAG291EXCHANGEINT_--

Problem:

Currently gitlab supports only

  • to
  • referece
  • delivered_to

as fields to find the service desk key. This can be easily read from https://gitlab.com/gitlab-org/gitlab/blob/master/lib/gitlab/email/receiver.rb .

Solution proposal

I think this could be handled quite easy. Inspired by !1810 (merged) i think a simple solution could be provided by adding a additional function

      def find_key_from_envelope_to_header(mail)
        Array(mail[:envelope-to]).find do |header|
          key = Gitlab::IncomingEmail.key_from_address(header.value)
          break key if key
        end
      end

and enhancing key_from_additional_headers

      def key_from_additional_headers(mail)
        find_key_from_references(mail) ||
          find_key_from_delivered_to_header(mail) ||
          find_key_from_envelope_to_header(mail) 
      end
Edited by Max Winterstein