RFC
It looks like Microsoft are getting pickier about email address syntax, rejecting mail that uses illegal address formats. That might be what’s causing that “550 5.6.0 CAT.InvalidContent.Exception: DataSourceOperationException, proxyAddress: prefix not supported – ; cannot handle content of message” rejection. Why do we care? It’s good to send syntactically valid email in a warm fuzzies sort of way – it shows we know what we’re doing, and aren’t dodgy spamware – but it’s increasingly important to delivery as mailbox providers are tightening up on their syntax checks. But why are mailbox providers doing that? One reason is that authentication tech like DKIM and DMARC is built around them only being applied to email. Not to messages that kinda look like email. There are ways to bypass DKIM protections by sending invalid messages. As one example, if you send multiple copies of the From: header with different values a DKIM checker
Independent Submission M. Kucherawy, Ed. Request for Comments: 7489 Category: Informational E. Zwicky, Ed. ISSN: 2070-1721 Yahoo! March 2015 Domain-based Message Authentication, Reporting, and Conformance (DMARC) Abstract Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a scalable mechanism by which a mail-originating organization can express domain-level policies and preferences for message validation, disposition, and reporting, […]
Network Working Group P. Resnick, Ed. Request for Comments: 5322 Qualcomm Incorporated Obsoletes: 2822 October 2008 Updates: 4021 Category: Standards Track Internet Message Format Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the […]
Network Working Group J. Klensin Request for Comments: 5321 October 2008 Obsoletes: 2821 Updates: 1123 Category: Standards Track Simple Mail Transfer Protocol Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the “Internet Official […]
The Japan Anti-Abuse Working Group (JPAAWG) held its second annual meeting in Tokyo, Japan on November 14th and 15th, 2019. DMARC.org director Steve Jones was invited to give a general update on DMARC and related matters, and the slides from that presentation are now available for download (with notes). The update covers a number of areas, including two new publications from the […]
The Authenticated Received Chain (ARC) was designed to address situations where email messages that are forwarded, and in some cases altered, will no longer pass email authentication checks. After spending 3 years as a work item in the IETF‘s DMARC Working Group, the specification was published as RFC 8617 (HTML, PDF, plain text) on July […]
The Japan Anti-Abuse Working Group (JPAAWG) held its first meeting in Tokyo, Japan on November 8th, 2018. DMARC.org director Steve Jones was invited to give a general update on DMARC and related matters, and the slides from that presentation are now available for download. The update covers several areas of interest to people working to […]