> On Apr 18, 2018, at 2:40 PM, Erwin <joc...@gmail.com> wrote: > > Hi, > > This may be old hat to some, but staring at the RFCs (specifically 2821) the > only conclusion I see is that Microsoft is (or at least *.outlook.com servers > are) violating the format of the Received headers here: > > Received: from mta.email.thinkgeek.com (66.231.88.32) by > SN1NAM04FT019.mail.protection.outlook.com (10.152.88.152) with Microsoft SMTP > Server (version=TLS1_0, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384) id > 15.20.675.14 via Frontend Transport; Mon, 16 Apr 2018 16:33:42 +0000 > > Should that IPv4 literal be enclosed with "[" and "]" tokens, either as > ([a.b.c.d]) or (hostname [a.b.c.d])?
According to the BNF yes, probably. In practice parsing Received headers is more about heuristics than a formal grammar, especially with comments^Wanything inside parentheses. Time-stamp-line = "Received:" FWS Stamp <CRLF> Stamp = From-domain By-domain Opt-info [CFWS] ";" FWS date-time From-domain = "FROM" FWS Extended-Domain By-domain = CFWS "BY" FWS Extended-Domain Extended-Domain = Domain / ( Domain FWS "(" TCP-info ")" ) / ( address-literal FWS "(" TCP-info ")" ) TCP-info = address-literal / ( Domain FWS address-literal ) address-literal = "[" ( IPv4-address-literal / IPv6-address-literal / General-address-literal ) "]" Cheers, Steve _______________________________________________ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop