Returns a span that is hidden in browsers but not hidden in the e-mail list in e-mail clients. In the list the Preheader is visible instead of the first 200 characters from the mail content.
The value is based on the Pre-header field in Email Marketing.
(Online Marketing - Email marketing - Folder - Edit email - Pre-header)
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.
The tag output is like this:
<span style="display: none !important; visibility: hidden; opacity: 0; color: transparent; height: 0; width: 0;">My preheader</span>