changing my site's domain name
mmelin: Assuming that Foo Inc. has not presented any demands as to when you have to cease control over foo.com, what you want to do is to set up a HTTP 301 redirect to your new domain phoo.com and leave it indefinitely. Human traffic will probably adapt to the new domain relatively quick, but search engines can take a while to update all instances of foo -> phoo even though 301 means "permanently moved".