Very recently we've had a number of occurrences where registration form URLs are being redirected to either a "404 page not found" or to a site called "topdomain.me". We test the campaigns before they go out, so it's become difficult to know when this is happening until a customer contacts us and lets us know. Has anyone encountered this, and if so, what could be causing this?
What kind of registration? Are the pages you're liking to hosted on your site? Are they Marketo landing pages? Are they a part of a 3rd party platform? If you could provide more information on the links, how they're created, how they're distributed, etc. it would be helpful.
Like Chris says, there isn't enough to go on here. You have to provide actual domains and actual links (including their original and rewritten versions) if you want us to get to the bottom of this.
A URL can end up 404ing because your site doesn't like long URLs -- or because your DNS is partially broken -- or multiple other reasons. As for topdomain.me that's particularly bizarre because it doesn't even exist.