I'm not sure I understand this. If you are sending a security deposit back to him on xx date, why not hit "reply" to his e-mail and say "security deposit to be mailed on xx date". That would have taken less time than it took to post your question. If he's asking other things that have nothing to do with you, delete them but I don't understand what he would be asking you something that doesn't pertain to you. Maybe I'm missing something.