Currently, Xplan can only apply a single DKIM / DMARC certificate per site. This means that Xplan will not support an individual practice on Compass or CWT using DKIM / DMARC in their DNS.
If a practice's DMARC were to be added at a site level, It would mean that every email being sent from Compass or CWT would have a DMARC signature applied as coming from that practice's DMARC. Because this is a lie, it would cause all other emails to be undelivered.
The current DMARC functionality can only work if every email coming from the XPlan site is coming from the same domain.
The ability to have multiple DKIM / DMARC certificates per site has been previously raised as an enhancement, but this has not been put on their roadmap. As such the practice will need to choose between having a DKIM/DMARC added to their DNS or having the functionality of sending emails through Xplan.
In order to best ensure your emails are delivered via Xplan, please refer to our Email Domain Xplan Set up Guide to update your SPF record, if you haven't already.