Branded URLs to non-Marketo landing page

Anonymous
Not applicable

Branded URLs to non-Marketo landing page

We have a email that has a link going to a page on our website (https://apply.veteransunited.com/blah).  When you click the link in the URL on a received email...sometimes the URL is apply.veteransunited.com/blah and sometimes it's go.vu.com/blah.  Why is this?  We do have a branded domain of go.vu.com setup for our landing pages but I was under the impression that a URL to a non-marketo landing page should not show as go.vu.com?  Could someone help me understand this?