When creating a new publication, Publitas is able to look for email addresses and web addresses in the copy of the pages and convert these into Link hotspots. If the PDF contains annotations that also link to a web address or a certain page of the document these will be converted to Link hotspots and Page-jump hotspots respectively.
The default hover text will be applied to all web addresses that are detected and converted to Link hotspots. For email addresses, the hover text will show the detected email address.
TIP: Make sure all visible web and email addresses are stored as text in the PDF (more info) and they appear in a single line of text (i.e. they do not overflow into the next line of text).