[GTALUG] We are having DMARC/DKIM troubles ...

[CLIFFORD ILKAY]

On 11/06/16 11:19 AM, Stewart C. Russell wrote:
> If replies seem patchy, we've just had a bunch of people - mostly Yahoo
> and Rogers users - auto-kicked from the list due to DMARC. This is an
> ongoing pain for list admins. The reason given by Yahoo is this:
>
>    https://help.yahoo.com/kb/postmaster/SLN7253.html
>
> Yeah, they're advising Reply-To mungeing as an industry standard. Joy!

I host a few Mailman lists and this is a never-ending source of problems 
for me. It's not just a Yahoo/Rogers issue. Rogers uses Yahoo behind the 
scenes anyway. It's also a problem with anything hosted by Microsoft, 
for example, Hotmail, Outlook.com, MSN, and Sympatico email accounts, 
though Microsoft's behaviour is even worse. The domains in question have 
SPF and DKIM set up and pass the usual tests. The IP address for the 
server isn't on any RBLs. Microsoft will accept the message from the 
list but it will NOT deliver the message anywhere.

I proved this by doing the following.

* Created a fresh outlook.com account.
* Subscribed that outlook.com account to a test mailing list that was 
configured identically to the other lists that I host.
* Sent a message to the test list as another subscriber.
* Confirmed that all non-Microsoft subscribers to the test list received 
the test message.
* Looked in the server's logs and saw that Microsoft accepted the 
message for delivery so as far as my server is concerned, it's job is done.
* Looked in the fresh outlook.com account and the message is nowhere to 
be found, not in the inbox, not in junk. I'm sure that violates an RFC. 
If you accept the message for delivery, you MUST deliver it somewhere, 
even if it is the junk folder. As far as Mailman is concerned, there was 
no bounce and everything is fine but the subscriber will never see messages.

For the outlook.com subscriber to see the messages from the list, I did 
the following.

* Added an address book entry for the list's address.
* Repeated the process above.
* Saw that the message had been delivered to the inbox.

Sometimes, the message will still get caught in outlook.com's junk 
filter and will end up in the junk folder. At least it is in a place 
that can be found. To work around that, create a rule that never sends 
messages from the list to junk.

This is obviously a problem for non-technical users. They simply do not 
understand any of this and it all becomes too complicated for them. Most 
users do not know how to add anything to their address book or create 
message filters/rules and they think the list server is broken and 
should be "fixed" when in fact, it's their email provider.

I never see these issues with subscribers who have Gmail accounts, by 
the way.

Email is dying a slow death. The alternatives, like Twitter direct 
messaging, Slack (ugh!), WhatsApp (double ugh!), and various instant 
messaging schemes are worse. Those will eventually be polluted by 
spammers, too.

-- 
Regards,

Clifford Ilkay

+ 1 647-778-8696

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