[Mailman-Users] Recent trouble with DMARC Munging

Mark Sapiro mark at msapiro.net
Tue Jan 17 14:04:09 EST 2017

On 01/17/2017 08:57 AM, Lindsay Haisley wrote:
> So inquiring minds want to know. Why is this a cPanel bug?

Because cPanel provides Mailman and Python as part of their
distribution. When they first upgraded to a Mailman that included DMARC
mitigations based on DNS policy lookups, they included dnspython in
their Python package.

They have apparently shipped a recent update that upgraded their Python
2.6 package with dnspython to Python 2.7 without it, thus breaking their
Mailman package.

> As I recall, as well, there were, at one point, not one but at least
> two DNS resolution modules available for python - dnspython, PyDNS, and
> now perhaps python-dns, which are similar but differ with regard to
> such trivia as the case of the module name in import directives, but
> which will surely cause exceptions if the calling conventions aren't
> strictly followed.

You are correct. Mailman as distributed by us requires dnspython and
won't work with PyDNS. python-dns is the RedHat/Centos name for PyDNS.

> This all underscores the problems of relying on other people's
> organization, and the resulting dependency on other people's confusion
> that comes from blind reliance on über-packages (especially proprietary
> über-packages) such as cPanel which obfuscate and complicate solutions
> to simple problems. The following quoted "explanation", presumably from
> cPanel, is a perfect example. Exactly _which_ python DNS module are we
> talking about here? It's clear as mud!

Agreed, but such packaged solutions have a place. I don't know what
Scott's situation is or his reasons for using cPanel, but I know Brian
operates a shared hosting service, and I know from his participation on
this list that he is conscientious in providing good service to his
customers, and without something like cPanel, his business might not be

>From my point of view, I think everyone should install Mailman from my
source. Then I wouldn't ever have to deal with issues caused by
downstream packagers, but that's unrealistic in the real world.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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