Most of what a clinic should automate is not marketing at all
The highest value automated communication in a healthcare setting is a recall. Somebody had a check a year ago, a cleaning six months ago, a review due at three months, a vaccination schedule with dates on it. Sending that reminder at the right interval is a service, and it happens to fill appointment slots. Almost everything else that gets called healthcare marketing is a long way behind it in both value and appropriateness.
That framing solves most of the ethical questions before they arise. If a send is derived from what happened to this individual and is due now, it is a recall. If it is derived from a monthly campaign calendar and goes to everyone, it is a broadcast and it needs a much higher bar. Practices that keep that distinction clear rarely get into trouble.