Hi, Kris. Yes, you can link documents within emails. We do this all the time for our manuals. When you test this, does the same thing happen to you (or others)? If not, it could be a matter of needing to clear the browser's cache.
If it's happening for everyone who registers, what page element did you use in the site designer? If you use the custom link element, the default URL is cvent.com. You'll want to double-check that you're removing the default link and pasting the document link there. (visual attached).
------------------------------
Sara Shidal
Computer Services, Inc
------------------------------