Seeking advice on mailing method for security deposit

[Melissa Robles]

Hi BP community! I'm looking for some advice on my current security deposit situation.

My former (very disagreeable and difficult) tenant moved out and I mailed his security deposit settlement to him at his new address via Certified Mail with Return Receipt within 30 days, as SC law requires. The mail carrier has attempted delivery twice and now the mail piece is on its way back to me, "unclaimed." The tenant has since explicitly stated in writing that he refuses to be inconvenienced by answering the door to the Mail Carrier or to go to the Post Office and pick it up/sign for it. He has reiterated to me that he has "not received the refund of [his] security deposit."

SC law does not dictate that I use Certified Mail, but considering his disagreeable nature, I feel it is best practice to protect myself by returning his deposit in this way (or similarly) with proof of mailing date and proof of delivery. 

I know that the cashed check would serve as proof that he received it, but I can't ignore the possibility that he will disagree with the deductions and refuse to cash the check, leaving me exposed to a lawsuit for failure to return the deposit timely.

What advice can you offer on what my next course of action should be?