Looking at MS documentation SMTP connectors are:
“Typically, the main reason for an SMTP connector is either to send mail a certain way to a certain domain (for example, to forward messages to a specific smart host for that domain only or to send HELO instead of EHLO) or to take the place of an IMS in an environment that includes Exchange Server 5.5.”
So I guess that if you’re using SBS these are automatically created or you’d have a look at your server’s configuration. Example are you using a smarthost in Exchange? If yes than this behavior is normal.