And what about css variables and calculations? Seems somewhat obvious how to do for most properties, are var() and calc() just properties or are they special in any way?
The event registration page has since changed so that event registration constitutes a global email opt-in. So I am dealing solely with this group of 150.
I am being asked to email this group of 150 about the event (directions, parking, day-of-event instructions, etc.). We would still respect the general unsubscribe and thus not include these people on our regular email list.
He's indicating the recipients directly acted in a way communicating their interest in the event.
100% kosher. Unsubscribe does not equal "do not email ever". They need this information. Maybe use a different IP/service/from name etc to differentiate.