Returns the subject of the e-mail.
The value is based on the Subject field in Email Marketing.
(Online Marketing - Email marketing - Folder - Edit email - Subject)
The EmailMarketing/EmailMessaging tags are not rendered for a normal page that is not used with Email Marketing. The tags are only rendered when the page is used in the context of an email from Email Marketing.
You can e.g. use the tags in a design page template and assign it to the page that you want to use for the E-mail marketing newsletter.