Re: [libreoffice-users] Re: Bouncing messages from users -AT- global.libreoffice.org

At 13:47 06/04/2020 +0900, Howard Barr wrote:
> On Fri, 3 Apr 2020, 09:01 , <users+owner@global.libreoffice.org> wrote:
> > Hi, this is the Mlmmj program managing the 
> > <users@global.libreoffice.org> mailing list.
> >
> > Some messages to you could not be delivered. If you're seeing this 
> > message it means things are back to normal, and it's merely for 
> > your information.
> >
> > Here is the list of the bounced messages:
> > - 55854
> > - 55855
>
> This happens a lot and always from the same users. I have added 
> these users to my contact info but that hasn't helped. I guess it's 
> my side as others are obviously getting them. What else can I try?

You wrote to me privately about this (from a different address) 
nearly two years ago. It's all down, I think to DMARC; see 
https://en.wikipedia.org/wiki/DMARC . This is a well-intentioned 
scheme to allow mail providers to reject incoming messages if they 
originate from a mail server which is not a registered server for the 
domain in the From: header. Such messages will generally be spoofed 
and thus spam, so this is a Good Thing. But a problem arises if 
mailing list processors (quite sensibly) preserve the original From: 
address on distributed messages - as does the LibreOffice Users list 
processor. The distributed message claims to be from the original 
sender (which it is, of course), but is sent via the LibreOffice mail 
server, which gives it the appearance of being a spoof message. You 
will fail to receive such messages if both (1) the originating mail 
domain publishes a list of approved servers and requires receiving 
systems to reject messages from elsewhere, and (2) your mail provider 
chooses to play ball and obey this requirement.

It must be that your mail provider satisfies condition (2), and the 
messages you will fail to receive are those whose mail domains 
satisfy condition (1). (Mine does this, so I'm having to send you a 
private copy of this message: you will presumably not receive the 
copy distributed via the list. I do not receive copies of my own 
contributions. The bounced messages above may well have been from me. 
Some others will )

There are solutions to this problem, the simplest of which is for the 
list processor to append something such as ".INVALID" to the From: 
address in relevant messages, so that they are no longer recognised 
as coming from a DMARC-conformant domain. Many mailing list providers 
do this. I wrote to <postmaster@documentfoundation.org> about this as 
long ago as 1 May 2018, but my suggestion for action was rejected, on 
the ground that "none of the workarounds [are] satisfactory for 
everyone". Thus the problem continues.

The present arrangement is unsupportable. You or others could start a 
campaign to have it put right.

Brian Barker  


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