Reject emails without DKIM Signature

doberman
Posts: 6
Joined: Fri Oct 20, 2017 1:12 pm
Location: Florida, USA

Reject emails without DKIM Signature

Postby doberman » Fri Oct 20, 2017 1:16 pm

Is there a way to block incoming emails that do not contain a DKIM signature? I've tried using the SPAM filter for "Where the message DKIM verification return results matching" and then choosing "Fail", but that is not catching emails that do not contain a DKIM signature.

Thanks!

doberman
Posts: 6
Joined: Fri Oct 20, 2017 1:12 pm
Location: Florida, USA

Re: Reject emails without DKIM Signature

Postby doberman » Mon Oct 23, 2017 10:49 am

The first filters in-line validate the SPF record, so this eliminates most of the spam.

I ended up creating a filter that checks the DKIM verification. If the verification comes back Fail or Intermediate, then I quarantine the email and manually check it's validity. Manually checking may sound like a pain, but this is a low volume mail server < 1000 emails per day.

Most of the quarantine items so far have been SPAM, but a few (ebay.com, gmail.com) need to be delivered. I could probably whitelist these domains so that I don't see then anymore in quarantine.

I've tried to activate Spam Protection, but it won't let me enable the feature, Professional version.

-Doberman

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