This website (example.com for confidentiality) has an odd open redirect situation. It redirects after logging in by a URL parameter like
I found that it allows you to change the redirect protocol to almost anything except a few windows protocols like mailto, so you can do something like:
However, as in the example above, *.example.com must be immediately after the protocol or it doesn't work.
Any ideas on common protocols where I could make my own malicious link and it would redirect to it?