Holds goodbye message sent to user when disconnecting.

A String value.  

object.GoodbyeMessage [= value]

The GoodbyeMessage Property syntax has these parts:

Although this may not seem like an important property, together with GreetingMessage this is usually very nice place to put some name/version information about your server to end users. For instance, it's default value is 'WeOnlyDo! SMTP server version ...' and is visible to anyone that connects to your server. Once you make Smtp a service publicly accessible, change it to your server name, put hostname, put some info important to users that connect or something similar.