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