[Linux-aus] PSA: Messages sent through LA mailing lists being classified as SPAM

Adam Nielsen a.nielsen at shikadi.net
Thu Jan 14 08:57:31 AEDT 2016

> Their spam engines are commercial in nature and whilst pretty
> accurate, do false-positive occasionally. It suggests that something
> about the email content/payload matches an email previously reported
> as spam to one of the engines concerned.

I run my own Spamassassin install and I've also had to whitelist
linux-aus otherwise many messages end up classified as spam.  This
isn't unique to linux-aus though, it affects many mailing lists.

> If one of the list administrators is able to capture one or more of
> the emails that was bounced, it can be sent to
> emailsupport at smxemail.com with the comment 'false positive' and they
> can re-check it and if still reporting as spam, attempt to correct
> this.  Otherwise a warning for anyone else employing anti-spam
> software.

I think the problem is DKIM/SPF combined with a mailing list.  Since
mailing list software adds "[linux-aus]" to the subject, and changes
the 'To' field, any sender using DKIM to sign messages will cause the
message validation to fail, as the modified message no longer matches
what the sender signed with their the DKIM key.

On top of that, anyone using SPF will see the e-mail comes from a Linux
Australia server which is not an authorized sender for that e-mail
domain, so that will also cause the message to be flagged as spam as
it looks no different to some compromised home PC sending spam from
that e-mail address also.

Last I checked there wasn't really a solution for this, because if you
strip the DKIM fields then the message will still fail.  Spam filters
check to see whether DKIM is expected on each message, so for those
hosts where DKIM is mandatory, missing DKIM fields will cause the
message to be marked as spam.

If any new developments have happened that might address this, please
let us know because this is a frequent problem with many mailing lists
I am on, ever since I enabled DKIM and SPF on my e-mail domain.


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