All states require that a landlord either return the security deposit or provide information regarding the status within a required time frame for that state.
New York is one of those states that has no specific time requirement, only requiring that this be done "within a reasonable amount of time" (hint: this time has now passed).
When a tenant skips, it is easy to forget to do this. For one thing, someone who sneaks out in the night rarely leaves a forwarding address.
In that case, you send the information to the last known address (i.e., your rental property) and if it is not forwarded, you collect the envelope and keep it UNOPENED in your files in the event that three years down the road your former deadbeat tenant tries to sue you for zillions of dollars for not doing this. You then have the evidence that you made the effort to provide them with this required information.
MANY a landlord who has had a deadbeat tenant skip out fails to do this and, as the ultimate insult, find themselves being sued down the road.