How many PortalAliases can you have and what is the separator?  The problem I was having is that when you click on my header, the URl was a list of all my Portal Aliases from the database and then the /default.aspx ... so when people went to my site and click on the header to take them back to the Home page.. it would come up with URI portal not found error.
Also, this list of Portal Aliases also showed up in the Site Marketing, Site Map URL:  it listed all my Portal Aliases and then /sitemap.apx.

Thanks
mike

There is no limit to the number of portal aliases - although there is a practical limit.

Remember for each alias you create an entire copy of your site under a different domain name. So example.com/ and example2.com are effectively two different websites in terms of the Urls being unique.

Duplicate domains lead to confusion with users, and often lead to poor search engine rankigns as well.

It's better to pick one portal alias and use that, and setup a redirect for any other domain names you might own.