The PDF file should be saved so the text is readable. To make sure the text is readable, open the PDF in Adobe Acrobat Reader and use the "Select" tool to try and highlight a section of the text. If the text can be highlighted then the PDF is saved correctly.
The text needs to be readable so that the software can make email and Web address links "hot" so that your readers can click on the links to either send an email or visit the website. If the text cannot be highlighted, the PDF is probably saved as an image and will not work properly in the system. The image below is an example of how not to save a PDF, as it saved as a JPG in this example.