Returned and Non Deliverable Yellow Letters

[Stephanie Bureau]

So I've sent out about 150 letters so far and have gotten back 16 as return to sender. I checked the addresses on the first few on the tax assessor's site and their correct. I got the info from listsource if that means anything.

I gotten a "forward time exp return to sender" (2) with a forward address so can I just send to the forward address instead?

"Attempted - not known, unable to forward" - 5

"Not Deliverable as addressed, unable to forward" - 7

"No such number, unable to forward" - 1

"Vacant, unable to forward" -1

Is there anyway I can find new/different addresses on these people? Is there something I need to check based on the reason they gave me? Or are these lost cases?