Lookup Last Date For Class With Specific Criteria?

I manage a list of web-based classes offered by my company - each class name, date, time, and attendance is recorded in the list. Periodically, we send out marketing emails for these classes to promote attendance, which is also recorded in the list.

Issue: I have a summary list of the class names (where each class is only listed once) and I'm trying to come up with a formula that will pull the class date for the last time that course was marketed.

I have attached an example of what I am trying to do - using colors instead of class names. The last date marketed for each color is already hard-keyed into the summary to show what should be there.