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[2620:137:e000::1:20]) by mx.google.com with ESMTP id dp18-20020a170906c15200b0072a477a55e0si14159782ejc.369.2022.10.13.05.41.05; Thu, 13 Oct 2022 05:41:33 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@wired4ever.net header.s=20220911-jt8y header.b=iSdfME4d; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=wired4ever.net Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229705AbiJMMjl (ORCPT + 99 others); Thu, 13 Oct 2022 08:39:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229513AbiJMMjk (ORCPT ); Thu, 13 Oct 2022 08:39:40 -0400 X-Greylist: delayed 472 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Thu, 13 Oct 2022 05:39:36 PDT Received: from wilbur.contactoffice.com (wilbur.contactoffice.com [212.3.242.68]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64A271D6; Thu, 13 Oct 2022 05:39:36 -0700 (PDT) Received: from smtpauth1.co-bxl (smtpauth1.co-bxl [10.2.0.15]) by wilbur.contactoffice.com (Postfix) with ESMTP id CC4AF1207; Thu, 13 Oct 2022 14:31:42 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1665664302; s=20220911-jt8y; d=wired4ever.net; i=sndanailov@wired4ever.net; h=From:Cc:Date:Message-Id:MIME-Version:Content-Transfer-Encoding; l=1945; bh=M9N/7nWDqlxLQOR6V0NKYvTK2UrdV1FKuUtNqKoS8Os=; b=iSdfME4dI2biXPD3Zob+E/iABuqzlwyLdEGcO+gCLGr9jseukiO8u8SYFxC3N9IC H+r2KL8tniACXYw4oSoe3yoFFIuYhnloytJaRGlY9EJfqhVVHImnKKdif86dOO3CcWr X3gRTIzMYYVJwIOwhaZdISIsFjsjNvSBaQQZSsIR+IHUwdGCqjG1UEhpwyPvAsWifb3 v9XkgPdCVgeDz8FP5nkPGalHy4e8KgbbCk0cln5I1iSZuLSLrRAzV+vEcLitqShft7V lND4cyuhC4B8/mkfInIBYyY1u6VjJCml0Up9r9OwkacYl5jWL9R2Y4v8o5haSUJ11pS fiCpimHfgA== Received: by smtp.mailfence.com with ESMTPSA ; Thu, 13 Oct 2022 14:31:40 +0200 (CEST) From: sndanailov@wired4ever.net To: corbet@lwn.net Cc: rdunlap@infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Sotir Danailov Subject: [PATCH] doc: process: add privacy warning when using some SMTP servers Date: Thu, 13 Oct 2022 14:31:15 +0200 Message-Id: <20221013123115.17419-1-sndanailov@wired4ever.net> X-Mailer: git-send-email 2.37.3 MIME-Version: 1.0 X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-ContactOffice-Account: com:378009619 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1746576231733185428?= X-GMAIL-MSGID: =?utf-8?q?1746576231733185428?= From: Sotir Danailov Warn the user about "Received" headers and how some SMTP servers use them by attaching the user's IP addresses, when using some email clients. Add suggestion on how to test this behavior and how to avoid it. Signed-off-by: Sotir Danailov --- Documentation/process/email-clients.rst | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/Documentation/process/email-clients.rst b/Documentation/process/email-clients.rst index fc2c46f3f82d..9c49f9b33fdb 100644 --- a/Documentation/process/email-clients.rst +++ b/Documentation/process/email-clients.rst @@ -350,3 +350,24 @@ although tab2space problem can be solved with external editor. Another problem is that Gmail will base64-encode any message that has a non-ASCII character. That includes things like European names. + +Privacy/Security +---------------- + +Keep in mind, that even if you're using a working email client, the SMTP +server might have configurations you don't like. + +For example, if you decide to use the Gmail SMTP server with the Thunderbird +client, the server will add your private and public IPs into "Received" +headers, which are attached to all of your sent emails. This is done +to avoid spam and to check where in the routing path an error might have +occurred. Gmail's web GUI client doesn't add your IPs, because it's sent from +Google's servers directly, not an external machine. Unfortunately the web +client is not good for sending patches. You can check if your IPs are present +in the headers by reading the raw email source. + +If you do not wish this behavior, you need to find a provider which doesn't +do it or configure and host a SMTP server yourself. + +If you're concerned, always first send an email to yourself, read the email +source and if you see no issues, continue to the mailing lists!