phpwebhosting.com and theplanet.com

[Jistan Idiot]

Can someone tell me if and how phpwebhosting.com and theplanet.com are
affilaited with each other?

One of my friends has been using phpwebhosting for a while and all of a
sudden this year he can't send me email. I figured out that it is
because phpwebhosting.com is now using an IP block that is (or was)
owned by theplanet.com which of course my spamlist blocks all of that
nasty crap.

Did one of these companies buy out or merge with the other? How else
could they have gotten theplanet.com IP addresses?