Filter Option For Contacts Sub Panel On Targets - Lists

Hello All,

I have big target lists with a lot of contacts and I would like to be able to filter them from the Contacts sub panel on the target list. I saw a few other posts on here that were kind of what I was looking for, but none of them worked, and none of them were exact. I am hoping that someone who knows how to do this can post a step by step on how to do it, with the code that is needed? I would be very grateful and I don’t even know where to start.