[Mailman-Users] Mailman + Exim + strange headers

[Natu]

On 05/20/2014 05:17 AM, Stephen J. Turnbull wrote:
> Natu writes:
>
>  > If there is a dkim signature and it fails google will treat it as
>  > spam
>
> Note that, taking your words literally, this is against the DKIM RFCs
> -- a failed signature is supposed to be treated the same as a lack of
> a signature.
>
> That doesn't mean that Google can't or doesn't use it.  In particular,
> if the percentage of spam in the "failed or no signature" class goes
> up (which it will if you start signing), your "failed or no signature"
> rating will slump.  That effect might be enough to send unsigned mail
> from your site to the spambucket.
>
> But you can be sure that a valid DKIM signature will improve your
> site's reputation.
>
>

I believe you are correct Stephen.  When I had the problem, in addition
to signing outbound messages, I also increased the level of spam
control.  In particular I have a small number of users that forward
their mail to gmail, and gmail was blocking us because of the spam that
was getting forwarded.  I suspect that it may only have effected the
forwarded email from those accounts.    I also made efforts to increase
spam detected and thus reduced the amount of forwarded spam.

With Yahoo, I was also getting complaints that I was sending them spam
(i.e. rejected mail from their smtp server).  I registered with yahoo's
complaint feedback loop, where they claim they will forward to you (the
registered Mail administrator for the domain) any email they receive
from your domain that they think is spam or that their users have
flagged as spam.  After I both turned on dkim and registered, I never
got a single complaint from them.  Note that we do NOT send any kind of
marketing mail from this mailserver.

One other thing that might cause problems with the freemail providers is
as follows:  If mailman sends a large number of messages to a freemail
provider that are almost the same, i.e. the exact same email, but
addressed to many different recipient, then they might think your are
sending bulk unsolicited mail.  Having your mailing list mail test
positive in DCC is probably a good indication that this is happening.  
There may be an option in mailman to ensure that outbound messages from
a single post don't all look identical.  If so, you could try turning
that on.

Also, if you are dealing with lists that send high volumes of email to
gmail, destination specific metering of your outbound mail, as well as
adjusting the number of recipients in a single smtp transmission may
help.  If you are running postfix, discussions about how to implement
this can be found in the postfix archives.

Nataraj