How Will I Know?

I recently had a conversation with a dear friend I've known for years about how he would let me know that he was sick or he was on his way to the other side. A sombre thought but I've been in this position before, where I haven't heard from a suitor I regularly see for a long time, and I start to wonder. Unfortunately, I've even had to check obituaries someone close has passed away. As I am in a profession that requires secrecy, I'm not always considered in the usual ways of communication. That's why I suggested that my friend could send me an email from a different address with a secret symbol or a text message that could disappear after being read. Some kind of unique signal that would let me know it's an intentional message. It would be great to have some sort of closure. If I come up with a better idea, I'll be sure to let you all know:)