Obviously with email protocols, the main way as far as I'm aware that addresses in the form @example.com are used, the protocol can simply provide the user part of that domain as part of the communication. But I was wondering if it's possible for a server to tell from just a ping, or HTTP request to say, email@example.com that someone used bob. I'm leaning towards yes, because there are some examples I've seen (Dyn DNS, the company, comes to mind) of domains like firstname.lastname@example.org
The reason for this is that I want to be able to enable users to wake up a service and I think that this is a relatively memorable way to assign this.
I'm guessing that the server at subdomain.example.com would recieve all connections to @subdomain.example.com