Return Address

[James Charles]

I started my Direct Mailing campaign few weeks ago. I received some calls back but no motivated seller as of yet. I also received a few return letters. Some stating the new address, others stating no such person, etc. So I did my research and found the new addresses or where the person/people is currently residing.  But there is this one particular reason why some of the mailing didn't get sent out; the reason was "Not deliverable as Addressed". I know it means someone moved out and didn't notify the USPS but when I double check in the Property Appraiser site for these returns it still show that a few of them is still living at the current mailing addresses. So my question is how do I find the correct mailing addresses for these leads or Are these leads worthless?