Emails from Zendesk.com going to Quarantine

We use a cloud based Helpdesk ticketing system called Zendesk. Emails that come from this system are sent from mailto:help@tridenttransport.com (our domain). The issue we are having is these email's when they have an picture attached, they get sent to quarentine. We have updated our SPF record to include Zendesk.com as a allowed to send on our behalf. I have created a transport rule to bypass the spam filter,. I have also added the help@ address to the allow list on the anti-spam policy. I have a case open with Microsoft but they are not helpful in resolving this issue. Does anyone have any other advise on this issue?