Yes, we set up DKIM/SPF. These emails are personal, not affiliated with our IP or company domain, so is that still a factor?
Also, we ran a real email to @gmail addresses, not using the test function. But it's good to know that tests may go to spam.
Our company was blacklistsed a year or two ago due to one of our computers contracting a virus and sent out a lot of bad emails, but we have changed our domain since then. Could that be the cause, even if it's a different domain?
I will definitely turn to Marketo Support to look into our shared IP as well.
Thanks for your feedback!!