New submission from Erik Quaeghebeur <pyt...@equaeghe.nospammail.net>:
Encoded-word is apparently used for header line folding sometimes. This appears to me as an abuse of this encoding technique. However, that is not the main issue: it also causes a violation of RFC 2074, as it also encodes message id's: https://tools.ietf.org/html/rfc2047#section-5 says “An 'encoded-word' MUST NOT appear in any portion of an 'addr-spec'.” and https://tools.ietf.org/html/rfc5322#section-3.6.4 says “The message identifier (msg-id) syntax is a limited version of the addr-spec construct enclosed in the angle bracket characters, "<" and ">".” This causes actual problems. Namely, email clients cannot parse the message id and so have trouble with generation of In-Reply-To and References headers or problems with thread reconstruction using these headers containing encoded-word versions of message ids. Minimal example: --- >>> import email >>> import email.policy >>> msg = email.message_from_string("""From: t...@example.com To: t...@example.org Subject: Test Date: Mon, 10 Aug 2020 22:52:53 +0000 Message-ID: <vi1pr09mb41911d8371e899c1fe78ee48fa...@abcdefghijklm.nmopqrst.uvwx.example.com> X-Some-Blobby-Custom-Header: 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 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" BODY """) >>> print(msg.as_bytes(policy=email.policy.SMTPUTF8).decode()) From: t...@example.com To: t...@example.org Subject: Test Date: Mon, 10 Aug 2020 22:52:53 +0000 Message-ID: =?utf-8?q?=3CVI1PR09MB41911D8371E899C1FE78EE48FA440=40abcdefghij?= =?utf-8?q?klm=2Enmopqrst=2Euvwx=2Eexample=2Ecom=3E?= X-Some-Blobby-Custom-Header: =?utf-8?q?DIZEglcw6TIh1uC2UrnNjWYqe8l/bYo0oxKG7?= =?utf-8?q?mBX38s1urzvCwQD30Q07DDJFgTVZWKbThu6hVjR53MTYAHYClHPt8UvyFPkAUIc8P?= =?utf-8?q?s1/R+HuSQ8gbR1R03sKoFAgPZKO+FKJ9bNbBb60THl81zSCsZiALwi4LLOqnf9ZIB?= =?utf-8?q?111G4/shFuWxRlPcsPJt72sn+tTHZqK9fRAyoK1OZCZMJmjQGysovicz1Xc6nOXHM?= =?utf-8?q?Qr2+suRwOJwSUqvsfkj8EEtzJGj7ICQ2GbgBaOjcof1AML4RCFy/vD5bG0Y8HQ2KE?= =?utf-8?q?T3SraTki4dPo+xMYSZVFEy/va4rYeynOXPfxXfHSyIFwB6gnH74Ws/XPk8ZxhAQ2w?= =?utf-8?q?Sy7Hvgg3tZ7HOmlLWg4A/vUGN+8RJlgn+hHtuCXnglv+fIKEhW36wcFotngSrcXUL?= =?utf-8?q?bTlqdE5zjuV5O7wNfgIShZnNhnPdLipslmZJGaa6RQpIonZbwUWCM8g9DZmSwo8g0?= =?utf-8?q?On0l20IVS9s6bUCddwRZ5erHx4eUZ4DGh4YyR2fgm0WsNVW8pVsAdFMClfAJYqyPE?= =?utf-8?q?qrDN91djfPYRZPMvzYWTAm8MAip6vDa1ZvzywDpGJYD3VwapLfgFy+AR0S/q/V1HH?= =?utf-8?q?RmSXx1oNLEedhAt0OkIxWxO8FvqNeEfMLVhxTk1g=3D=3D?= MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" BODY --- ---------- components: email messages: 375397 nosy: barry, equaeghe, r.david.murray priority: normal severity: normal status: open title: encoded-word abused for header line folding causes RFC 2047 violation type: behavior versions: Python 3.7 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue41553> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
