I believe M1 or at least that is what it says in our admin panel.
If you are having Marketo sign email, but your DKIM DNS record does not exist -- and m1._domainkey.longboardmutualfunds.com does not exist -- that's going to be very bad. It's a mandatory PERMFAIL for DKIM.
Since I don't have access to your Mkto instance, I took the absence of the DKIM record to mean you weren't attempting to sign. Not signing means your mail will lack that little "oomph" of accountability+certification that can get it in the inbox if it is otherwise on the edge. But simply sending unsigned mail isn't going to mark all your outgoing email as spam. The majority of email across the net, bear in mind, is not signed.
On the other hand, telling Marketo to sign without having a corresponding DNS record so recipients can verify the signature is a disaster. Sounds like your problem right there!