* If you use the free ones (i.e. user.yourhda.com, [http://www.no-ip.org no-ip.org]), you will have to masquerade your email address as your ISP (i.e. myhda@yourisp.com). This will ensure you can receive email replies from those you send from your HDA.
* To permanetly change your hostname, see this [http://www.labtestproject.com/using_linux/permanently_change_hostname_on_fedora article].