You can set properties for a JavaMail Session object. Every property name must start with a mail- prefix. The GlassFish Server changes the dash (-) character to a period (.) in the name of the property and saves the property to the MailConfiguration and JavaMail Session objects. If the name of the property doesn’t start with mail-, the property is ignored.
For example, if you want to define the property mail.from in a JavaMail Session object, first define the property as follows:
Name – mail-from
Value – email@example.com