So I have this one website for a client with a reeeally long domain name - like 25 or 30 characters. I parked a much better domain name, only 13 characters, so they both point to the same server. Let's call them LongDomain.com and ShortDomain.com

The problem is, all my client's business cards now have LongDomain.com on them. When they navigate to that site, they might not understand if I just redirected them to the ShortDomain.com - that's not where they wanted to go, as far as they know. So users who go to LongDomain.com should see the site as LongDomain.com, and users who go to ShortDomain.com should see it as ShortDomain.com. In fact, that's how parking works by default anyway.

Okay, so then they go to the "Contact Us" page and see a bunch of emails. If you're on LongDomain.com and see contactus@ShortDomain.com, isn't that kind of messed up?

To fix this I might just have all requests to LongDomain.com get redirected to ShortDomain.com, so ShortDomain.com shows up in the browser's address bar and everything. Or I could just allow them to navigate using either URL and choose one URL to use consistently across the site for things like email addresses. Which do you normally do in this case?

Along these same lines, Mitch, I have a domain called http://bestheartnuts.com  and I put in a pice of html code in the add on domain and named it index.htm  But, I also added some meta tags in this simple redirect index.htm where it goes to jenefarm.com  I know I can do a redirect within cpanel, but I was thinking that if someone was looking for heartnuts, it might steer them into the site that is possibly more useful, rather than leave it as a simple parked domain or as one that ususally gets sent in search engines to site and info on hearts, and not necessarily hearnuts.  (Heartnut is a Japanese walnut that seems to thrive in the Great Lakes region of the North East). 

Is this a violation of search engines?  This is a simple redirect html code: 
<meta HTTP-EQUIV="REFRESH" content="5; url=http://www.yourdomain.com/index.htm">
<p>Redirecting you in 5 seconds......</p>

You can put any value in the spot other than 5  5 is the number of seonds before redirecting.  0 and it redirects immediately.  You can also put in a bit more text such as " Redirecting you in 5 seonds to the main site of jenefarm ..... please wait."  or whatever.