Nah, if you had it handy, probably not worth the trouble. There is a general problem in mail clients, which is that they mostly present a single field to users expecting a series of addresses, but actually expecting users to properly escape those is kind of insane. The work around tends to be to try and match the entry to an address book or imply to the user that we've "accepted" an address in real time, but it still leaves a lot of leeway for having to use heuristics.
In theory, those heuristics shouldn't be used when parsing the actual message at smtp time, but sometimes there are leaks between the two versions.... especially because a lot of folks compose email messages poorly as well (it's just text, who needs to use a library?) Brandon On Tue, Dec 14, 2021 at 10:29 AM Richelo Killian <richelo.kill...@imnica.com> wrote: > Hey Brandon, > > Yes, all messages had 100% valid headers, and a single from address. > > I connot remember which special characters exactly caused this bounce. It > wasn’t all of the special characters, just 2 or 3 from my testing. Sure I > can run it again and confirm if you like. > > Kind Regards, > > Richelo Killian > > From: Brandon Long <bl...@google.com> <bl...@google.com> > Reply: Brandon Long <bl...@google.com> <bl...@google.com> > Date: December 14, 2021 at 19:43:16 > To: Richelo Killian <richelo.kill...@imnica.com> > <richelo.kill...@imnica.com> > Cc: mailop@mailop.org <mailop@mailop.org> <mailop@mailop.org> > Subject: Re: [mailop] Gmail rejects multiple From:'s. Who else? > > If we sent you this message, our parser believed that you were sending us > two or more addresses in the from header. I would be semi-curious if you > had a valid rfc2822 (or later) address that we thought was two addresses. > > Brandon > > On Tue, Dec 14, 2021 at 12:19 AM Richelo Killian via mailop < > mailop@mailop.org> wrote: > >> When I ran into those messages in the past from Google, the messages >> actually did not have multiple from addresses. It turns out the issue was >> the friendly from part had certain special characters in it. Not all >> special characters, but certain ones do trigger this bounce mesage. >> >> So check that first before digging any deeper. I went down this rabit >> hole ;-) >> >> Kind Regards, >> >> Richelo Killian >> >> From: Alessandro Vesely via mailop <mailop@mailop.org> >> <mailop@mailop.org> >> Reply: Alessandro Vesely <ves...@tana.it> <ves...@tana.it> >> Date: December 14, 2021 at 09:55:41 >> To: mailop@mailop.org <mailop@mailop.org> <mailop@mailop.org> >> Subject: Re: [mailop] Gmail rejects multiple From:'s. Who else? >> >> On Mon 13/Dec/2021 18:51:48 +0100 Brandon Long wrote: >> > On Mon, Dec 13, 2021 at 9:46 AM Slavko via mailop <mailop@mailop.org> >> wrote: >> >> Dňa Mon, 13 Dec 2021 18:19:07 +0100 Alessandro Vesely via mailop < >> mailop@mailop.org> napísal: >> >> >> >>> Is it customary to reject messages with multiple addresses in From:? >> >>> Why? >> >> >> >> AFAIK, DMARC works with only one From: address, thus sites which >> >> are verifying DMARC tends to reject multiple addresses in it. >> > >> > Basically, yes, DMARC doesn't handle multiple from addresses, otherwise >> one >> > could do From: m...@whatever.com, accou...@google.com and which domain >> would >> > this be considered from? I guess one could evaluate DMARC for both. >> >> >> Evaluating both doesn't make much sense, because a DMARC receiver is >> actually >> verifying proper sending from the author's domain. The author who added >> one or >> more coauthors in the From: line is still sending through her usual MUA >> and >> submission server. Thus that's the only domain which is worth verifying. >> >> A Sender: line should point to the right domain. However, I'd propose >> that the >> sender be the first address in the From: line, which grants visibility >> and >> simplifies verifiers' code. >> >> >> > We also reject multiple From headers, which is much more common but >> > basically always an error or spam. >> >> >> Yes, that's explicitly forbidden and a known DKIM vulnerability (DKIM >> signers >> should specify From: twice in h=). >> >> >> Best >> Ale >> -- >> >> >> >> >> >> >> >> >> _______________________________________________ >> mailop mailing list >> mailop@mailop.org >> https://list.mailop.org/listinfo/mailop >> >> _______________________________________________ >> mailop mailing list >> mailop@mailop.org >> https://list.mailop.org/listinfo/mailop >> >
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