Quarantine unsigned e-mails from own domain

Joern Bredereck

Renowned Member
Mar 25, 2016

we receive spoofed phishing emails that appear to be coming from our own domain. In order to filter or quarantine those spoofed emails I activated DKIM signatures for our own emails. Now that all "legitimate" e-mails from our domain are digitally signed via DKIM I was hoping I could filter or quarantine all e-mails from our domain that don't have a valid DKIM signature. But so far I haven't been able to create an appropriate filter in PMG.

Could someone help me, setting up a filter in PMG that would quarantine all e-mails from a certain domain, that don't have a (valid) DKIM signature?

Thanks in advance!

you could increase the spamassassin score for that rule (something like DKIM_INVALID) but there is not really a filter for that
alternatively you could implement a dmarc policy on your domain too so failed dkim gets an even higher score out of the box


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