Mailman incompatibility with DKIM ...

Mailman incompatibility with DKIM ...
2015-06-19  9:56 ` Mike Hearn
  
From: Warren Togami Jr. @ 2015-06-19  9:51 UTC (permalink / raw)
  To: Bitcoin Dev

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Both you and jgarzik experienced mail getting tossed into gmail's spam
folder thanks to DKIM... I am concerned that DKIM is too fragile and not
very compatible with mailing lists.

We already removed the footer because it was incompatible with DKIM
signing.  Keeping the "[Bitcoin-dev] " prepend tag in subject is compatible
with DKIM header signing only if the poster manually prepends it in their
subject header.

I am already concerned that the lack of the Mailman footer will make it
hard to identify where exactly subscribers need to go to unsubscribe or
look at archives.  Removing the subject tag might make DKIM enforcement
work a lot better, but I can easily see our obtuse subscribers as being
extra confused by this.

Opinions?

Warren

On Thu, Jun 18, 2015 at 11:38 PM, Arthur <arthur@powaaa•com> wrote:

> warren | bad_duck: try manually adding "[Bitcoin-dev] " to the beginning
> of the subject
>
> --
> Arthur
>

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2015-06-19  9:51 [Bitcoin-development] Mailman incompatibility with DKIM Warren Togami Jr.

  2015-06-19 10:10   ` Warren Togami Jr.
  
From: Mike Hearn @ 2015-06-19  9:56 UTC (permalink / raw)
  To: Warren Togami Jr.;  Bitcoin Dev

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>
> We already removed the footer because it was incompatible with DKIM
> signing.  Keeping the "[Bitcoin-dev] " prepend tag in subject is compatible
> with DKIM header signing only if the poster manually prepends it in their
> subject header.
>

I still see footers being added to this list by SourceForge?


> Opinions?
>

I've asked Jeff to not use his @bitpay.com account for now.

The only real fix is to use a mailing list operator that is designed to
operate correctly with DKIM/DMARC, either by not modifying messages in
transit, or by re-sending (and ideally re-signing) under their own identity.

Though I'm sure this won't be an issue for the Linux Foundation, the latter
approach is dangerous because it means the list operator takes full
responsibility for any spamming that occurs from that domain. If the mail
server is ever hacked or spammers start posting to the lists themselves,
all that spam will be seen as originating from the listserv itself and the
reputation will be degraded. It can end with everyone's mail going to the
spam folder.

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2015-06-19  9:56 ` Mike Hearn

  2015-06-19 10:24     ` Mike Hearn
  
From: Warren Togami Jr. @ 2015-06-19 10:10 UTC (permalink / raw)
  To: Mike Hearn;  Bitcoin Dev

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On Thu, Jun 18, 2015 at 11:56 PM, Mike Hearn <mike@plan99•net> wrote:

> We already removed the footer because it was incompatible with DKIM
>> signing.  Keeping the "[Bitcoin-dev] " prepend tag in subject is compatible
>> with DKIM header signing only if the poster manually prepends it in their
>> subject header.
>>
>
> I still see footers being added to this list by SourceForge?
>

The new list currently has footers removed during testing.  I am not
pleased with the need to remove the subject tag and footer to be more
compatible with DKIM users.


>
>
>> Opinions?
>>
>
> I've asked Jeff to not use his @bitpay.com account for now.
>
>
I'm guessing DKIM enforcement is not very common because of issues like
this?

It seems that Sourceforge silently drops DKIM enforced mail like
jgarzik's.  LF seems to pass along their mail but mangles the header/body
and makes DKIM verification fail, which causes gmail to toss it into the
spam folder.  I think this behavior is slightly worse than Sourceforge
because it makes the poster think their message was successfully sent (it
is in the archive), but many subscribers never see it due to the spam
binning.

I don't see any good solution to this except an auto-reject for DKIM
enforced domain postings.  Yes this is rather terrible, but the instant
rejection is vastly better than Sourceforge silently dropping the post or
LF getting stuck in spam filters.

We should also auto-reject any other reason for mail getting stuck in the
moderation queue like including non-subscribers.  I considered
auto-rejecting spam too, but that could go horribly wrong as a false From
address could make the Mailman server into a spammer itself.  We may have
no choice but to silently drop spam for that reason.

Warren

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2015-06-19 10:10   ` Warren Togami Jr.

  2015-06-19 10:38       ` Warren Togami Jr.
  
From: Mike Hearn @ 2015-06-19 10:24 UTC (permalink / raw)
  To: Warren Togami Jr.;  Bitcoin Dev

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>
> The new list currently has footers removed during testing.  I am not
> pleased with the need to remove the subject tag and footer to be more
> compatible with DKIM users.
>

Lists can do what are effectively MITM attacks on people's messages in any
way they like, if they resign for the messages themselves. That seems fair
to me!  :)


>  I'm guessing DKIM enforcement is not very common because of issues like
> this?
>

DKIM is used by most mail on the internet. DMARC rules that publish in DNS
statements like "All mail from bitpay.com is signed correctly so trash any
that isn't" are used on some of the worlds most heavily phished domains
like google.com, PayPal, eBay, and indeed BitPay.

These rules are understood and enforced by all major webmail providers
including Gmail. It's actually only rusty geek infrastructure that has
problems with this, I've never heard of DKIM/DMARC users having issues
outside of dealing with mailman. The vast majority of email users who never
post to technical mailing lists benefit from it significantly.

Really everyone should use them. Adding cryptographic integrity to email is
hardly a crazy idea :)


> It seems that Sourceforge silently drops DKIM enforced mail like jgarzik's.
>

It's not SourceForge, it's your spam filter. His mail gets through to me
but it's all in the spam folder.

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2015-06-19 10:24     ` Mike Hearn

  2015-06-19 10:49         ` Mike Hearn
  2015-06-19 19:47         ` Adam Weiss
  
From: Warren Togami Jr. @ 2015-06-19 10:38 UTC (permalink / raw)
  To: Mike Hearn;  Bitcoin Dev

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On Fri, Jun 19, 2015 at 12:24 AM, Mike Hearn <mike@plan99•net> wrote:

> The new list currently has footers removed during testing.  I am not
>> pleased with the need to remove the subject tag and footer to be more
>> compatible with DKIM users.
>>
>
> Lists can do what are effectively MITM attacks on people's messages in any
> way they like, if they resign for the messages themselves. That seems fair
> to me!  :)
>

Mailman isn't resigning it.  Should it be?  Does other mailing list
software?


>
>
>>  I'm guessing DKIM enforcement is not very common because of issues like
>> this?
>>
>
> DKIM is used by most mail on the internet. DMARC rules that publish in DNS
> statements like "All mail from bitpay.com is signed correctly so trash
> any that isn't" are used on some of the worlds most heavily phished domains
> like google.com, PayPal, eBay, and indeed BitPay.
>
> These rules are understood and enforced by all major webmail providers
> including Gmail. It's actually only rusty geek infrastructure that has
> problems with this, I've never heard of DKIM/DMARC users having issues
> outside of dealing with mailman. The vast majority of email users who never
> post to technical mailing lists benefit from it significantly.
>
> Really everyone should use them. Adding cryptographic integrity to email
> is hardly a crazy idea :)
>

I understand the reason to protect the "heavily phished" domains.  I heard
that LKML does not modify the subject or add a footer, perhaps because it
would make it incompatible with DKIM of the several big corporate domains
who participate.

I suppose it is somewhat acceptable for us to remove subject tags and
footers if we have no choice...

Warren

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2015-06-19 10:38       ` Warren Togami Jr.

  2015-06-19 19:47         ` Adam Weiss
  
From: Mike Hearn @ 2015-06-19 10:49 UTC (permalink / raw)
  To: Warren Togami Jr.;  Bitcoin Dev

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>
> Mailman isn't resigning it.  Should it be?  Does other mailing list
> software?
>

Mailman must take responsibility for the mail itself. It doesn't have to
actually sign with DKIM to do so: for backwards compatibility, spam filters
fall back to other heuristics to try and figure out the 'owner' of the mail
if it doesn't use DKIM. Those heuristics can go wrong of course. Ideally
all mail would be DKIM signed. There's no reason not to do it, really.

Yes mailing lists that edit people's emails resign. For example, from a
recent message to the bitcoinj list

DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        *d=googlegroups.com <http://googlegroups.com>*; s=20120806;
        h=to:from:subject:date:lines:message-id:references:mime-version
         :content-type:user-agent:in-reply-to:x-original-sender
         :x-original-authentication-results:reply-to:precedence:mailing-list
         :list-id:list-post:list-help:list-archive:sender:list-subscribe
         :list-unsubscribe;



> I suppose it is somewhat acceptable for us to remove subject tags and
> footers if we have no choice...
>

Good email clients can extract the same information from the headers
anyway. I filter all my mail based on them, and the headers also contain
unsubscribe instructions. Gmail is capable of using them programmatically.

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2015-06-19 10:38       ` Warren Togami Jr.
  2015-06-19 10:49         ` Mike Hearn

  2015-06-19 20:44           ` Jeff Garzik
  
From: Adam Weiss @ 2015-06-19 19:47 UTC (permalink / raw)
  To: Warren Togami Jr.;  Bitcoin Dev

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Hi Warren,

If you set dmarc_moderation_action to "Munge from", the list will detect
when someone posts from a domain that publishes a request for strict
signature checking for all mails originating from it (in DNS) and rewrite
the envelope-from to the list's address.  Reply-to will be added and set to
the original sender.

I think that this is probably a better way to workaround the issue (rather
than playing with getting the list to not break the signature) until these
things mature further.

Thoughts?

--adam




On Fri, Jun 19, 2015 at 6:38 AM, Warren Togami Jr. <wtogami@gmail•com>
wrote:

> On Fri, Jun 19, 2015 at 12:24 AM, Mike Hearn <mike@plan99•net> wrote:
>
>> The new list currently has footers removed during testing.  I am not
>>> pleased with the need to remove the subject tag and footer to be more
>>> compatible with DKIM users.
>>>
>>
>> Lists can do what are effectively MITM attacks on people's messages in
>> any way they like, if they resign for the messages themselves. That seems
>> fair to me!  :)
>>
>
> Mailman isn't resigning it.  Should it be?  Does other mailing list
> software?
>
>
>>
>>
>>>  I'm guessing DKIM enforcement is not very common because of issues like
>>> this?
>>>
>>
>> DKIM is used by most mail on the internet. DMARC rules that publish in
>> DNS statements like "All mail from bitpay.com is signed correctly so
>> trash any that isn't" are used on some of the worlds most heavily phished
>> domains like google.com, PayPal, eBay, and indeed BitPay.
>>
>> These rules are understood and enforced by all major webmail providers
>> including Gmail. It's actually only rusty geek infrastructure that has
>> problems with this, I've never heard of DKIM/DMARC users having issues
>> outside of dealing with mailman. The vast majority of email users who never
>> post to technical mailing lists benefit from it significantly.
>>
>> Really everyone should use them. Adding cryptographic integrity to email
>> is hardly a crazy idea :)
>>
>
> I understand the reason to protect the "heavily phished" domains.  I heard
> that LKML does not modify the subject or add a footer, perhaps because it
> would make it incompatible with DKIM of the several big corporate domains
> who participate.
>
> I suppose it is somewhat acceptable for us to remove subject tags and
> footers if we have no choice...
>
> Warren
>
>
> ------------------------------------------------------------------------------
>
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists•sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
>

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2015-06-19 19:47         ` Adam Weiss

  2015-06-20 18:43             ` Adam Weiss
  
From: Jeff Garzik @ 2015-06-19 20:44 UTC (permalink / raw)
  To: Adam Weiss;  Bitcoin Dev

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On Fri, Jun 19, 2015 at 12:47 PM, Adam Weiss <adam@signal11•com> wrote:

> Hi Warren,
>
> If you set dmarc_moderation_action to "Munge from", the list will detect
> when someone posts from a domain that publishes a request for strict
> signature checking for all mails originating from it (in DNS) and rewrite
> the envelope-from to the list's address.  Reply-to will be added and set to
> the original sender.
>

That seems to change Reply behavior for those recipients?  It would seem to
accidentally direct mail intended to DKIM-user + list to DKIM-user.

-- 
Jeff Garzik
Bitcoin core developer and open source evangelist
BitPay, Inc.      https://bitpay.com/

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2015-06-19 20:44           ` Jeff Garzik

  
From: Adam Weiss @ 2015-06-20 18:43 UTC (permalink / raw)
  To: Jeff Garzik;  Bitcoin Dev

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It changes the mechanics at least.  A quick glance at RFC(2)822 makes it
clear that this is a pretty weakly specified behavior and is somewhat of an
edge case.  However, rewriting the envelopes has become somewhat prevalent
since strict DMARC has been adopted and I suspect that most recent MUAs
will handle it well.  I know that at least with gmail it works as I would
expect.  (Makes sense considering that this is how Google Groups handles
the problem.)

In any event, I really think it's worth a shot since having the subject and
footer tags is valuable. If it turns out to be problematic, it's not the
end of the world and things could be easily switched to go the lkml route...

--adam


On Fri, Jun 19, 2015 at 4:44 PM, Jeff Garzik <jgarzik@bitpay•com> wrote:

> On Fri, Jun 19, 2015 at 12:47 PM, Adam Weiss <adam@signal11•com> wrote:
>
>> Hi Warren,
>>
>> If you set dmarc_moderation_action to "Munge from", the list will detect
>> when someone posts from a domain that publishes a request for strict
>> signature checking for all mails originating from it (in DNS) and rewrite
>> the envelope-from to the list's address.  Reply-to will be added and set to
>> the original sender.
>>
>
> That seems to change Reply behavior for those recipients?  It would seem
> to accidentally direct mail intended to DKIM-user + list to DKIM-user.
>
> --
> Jeff Garzik
> Bitcoin core developer and open source evangelist
> BitPay, Inc.      https://bitpay.com/
>

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