Holds hostname of local computer, for the relay.

A String value.  

object.MyHostname [= value]

The MyHostname Property syntax has these parts:

MyHostname property holds hostname of local computer to provide when relay sends HELO/EHLO command to remote server. When relay is created, this property is copied from SmtpServer.MyHostname property, but you can change it if you have multi homed server and wish to announce each relay differently.