DKIM ADSP validation increasing spam score

[rickyromero]

I use MailRoute for spam filtering. As of the past couple of months, I've noticed that some domains I route through Spamgourmet have had their spam scores increase. As a result, their emails get stuck in quarantine.

The messages which consistently get quarantined are sent from Amazon, eBay and PayPal. Digging into the headers, the X-Spam-Status rules which appear to be the culprits are:

Code: Select all

DKIM_ADSP_ALL=10
DKIM_ADSP_DISCARD=10

So, there appears to be a DKIM ADSP validation step in my mail filters which fails because Spamgourmet modifies incoming messages in a way that invalidates the DKIM signature.