The domains that are available for Pobox aliases are:
@pobox.com
@aliencamel.com
@foobox.com
@foobox.net
@immerbox.com
@immermail.com
@lifetimeaddress.com
@mailzone.com
@onepost.com
@penguinmail.com
@permanentmail.com
@rightbox.com
@siemprebox.com
@siempremail.com
@veribox.net