The page index.html that the user accesses to send an email, contains a form for the email and the following text:
"The default configuration assumes that there is an SMTP server running on localhost. If this is not the case, edit your mail.properties file and change the value for the mailhost parameter to the name of a host that provides SMTP service for your network, and change the value for the mailuser parameter to the valid mail user id, redeploy the application, and restart GlassFish."
As Eric noted, GlassFish already has an email server, so the user does not need to do any of that to run this example. The text above is confusing because it may have the user try to install a local SMTP server or go play with the mail.properties file when this is unnecesary.