Sent deposit receipt, came back as Undeliverable

Hi all,

First, I live in GA, just to get locale established. We have 30 days to send itemized deposit receipts. The tenant I just got rid of... I went through his deposit in a day in terms of damages. I'm also planning on suing him for everything else.

My issue is that when I sent out the letter showing all the damages/back rent and that I used his SD for it, the letter was returned as undeliverable. Before he left, he gave me an address as his forwarding address, and I used that address. I really don't care about him never receiving this letter saying that I used all of his deposit, especially since I can just hand the unopened, returend letter to a judge and say "here's the letter, here's his address that he gave me to forward, notice the undeliverable aspect". The real problem for me is that when I go to sue, I feel like I actually need his address when I put him down as the defendant, at the very least so that the sheriff could serve him. Can anyone advise on this issue? Thanks!