[Gluster-infra] [gluster-infra] The black art of mailing lists?

[Michael Scherer]

Le lundi 13 février 2017 à 02:09 +0100, Michael Scherer a écrit :
> Le samedi 11 février 2017 à 01:51 +0100, Amye Scavarda a écrit :
> > Hey there,
> > Getting a few pings on 'I've been unsubscribed from gluster-users@'  - and
> > my mailman-fu is pretty limited.
> > 
> > Anyone noticed anything odd in the mailman install? This started on
> > Thursday, Feb 9 as far as I can tell.
> 
> Hi,
> 
> mailman processes are here, so could you provides a bit more information
> like "who did ping" (so we can start to see if there is a pattern, etc),
> or even better, direct people to contact the list and/or open a bug
> report so this can be tracked properly ?

So, I did search more after reading all my emails, and the answer is
long but can be summarized by "yahoo and google suck, and we are in the
middle".

It seems that someone used a yahoo email to post on gluster-users. So
far, so good, but Yahoo do have a specific DMARC policy that prevent
sending email from yahoo from a non yahoo server. It also break mailling
lists for provider who do respect DMARC policy:
https://thehackernews.com/2014/04/yahoos-new-dmarc-policy-destroys-every.html

And among the ones that do strongly verify DMARC (instead of using it as
a indicator, since that's slightly less prone to breakage) is gmail, who
just block at the smtp level mail if the dmarc policy say so.


Usually, this is not a problem, since email just get dropped after a
while. 

But this time, my hypothesis is that the person who did post did send
enough to trigger a threshold in mailman to unsubscribe people (ie, more
than 5 bounces). So all the gmail subscribers got removed.

But we have logs, so I am gonna resubscribe everybody.

From here, we have several solutions:
- raise the bounce limit to 10. This doesn't fix the issue, but should
minimize it for the time being 

- make sure people who use yahoo email can't subscribe. If their email
provider break the list and can't work, we can't do much

- get someone fix gmail.com to be smarter about dmarc. There is likely a
lot more people impacted than us by this problem, and that's not the
first time Gmail is just doing crap stuff in the name of "spam
prevention". 

- fix mailman to be smarter regarding bounces. While 5 rejection is
indeed sign something is wrong, lots of regular email have been sent in
the mean time, so maybe there is something to do here. Maybe we were
just unlucky.


-- 
Michael Scherer
Sysadmin, Community Infrastructure and Platform, OSAS


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