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Subject: Re: [boost] Mangled "From" field in mailing list posts
From: Michael Caisse (mcaisse-lists_at_[hidden])
Date: 2017-06-13 22:17:00

On 6/13/17 01:22, Vladimir Prus via Boost wrote:
> On 12/06/2017 23:32, Michael Caisse via Boost wrote:
>> On 6/11/17 06:48, Stefan Seefeld via Boost wrote:
>>> The "From:" field could contain the full address of the original poster,
>>> not just his name. That's how things were before the change, IIUC.
>>> But, AFAIU, that had to change because some mail servers would refuse to
>>> serve mail whose "From:" address differed from the "sender" field (which
>>> is the list address in our case). Am I describing this correctly ? I
>>> wonder how others handle this situation (in particular, how mailman and
>>> similar tools deal with this themselves), given how frequent a use-case
>>> this is...
>>> Stefan
>> With the old system, many people were having issues with DMARC filtering
>> emails as-if they were spoof'd. In the recent couple years many
>> corporate accounts have moved to utilize DMARC as part of their inbound
>> authentication and the popularity continues to increase.
>> Unfortunately, Mail Lists normally break because the original sender's
>> domain DKIM signature doesn't match the Mail List. The most popular work
>> around is rewriting the From header field. We are doing that in the most
>> basic manner.
> Hi Michael,
> thanks for the explanation. So, if I understand correctly, the problem
> is that some *senders* have their domains configured to ask recipients
> to reject emails that don't pass DKIM or SPF? In other words, the
> question is not how many organizations have DMARC for inbound
> authentication, but how many users are sending emails to a mailing list
> (which, by definition, forwards email with modifications) while also
> requesting than any forwared with modifications emails are rejected by
> recipients? How many such sending users/domains do we have?

I might have explained poorly. When the ML sends emails, it is the
receiving side (inbound) that is doing the check. The receiving server
confirms headers, checks the signature against what is in the original
sender's domain entries and then fails the message.

Some of the organizations/services that utilize DMARC: Microsoft, Yahoo,
Pixar, any thing through Rackspace, and gmail.

We are talking about some other solutions... but most of them are
horrible or short lived until the entire world moves to DMARC.


Michael Caisse
Ciere Consulting

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