Toadkicker welcome to the forums, looks like it's trying to resolve mail.stevevalenti.us see if you can change it to just stevevalenti.us when the installer asks if you'd like to try another domain instead.
Externally both mail.stevevalenti.us & stevevalenti.us have mx records that point to cnames, it should be pointing at an actual IP A record.
stevevalenti.us > mx mail.stevevalenti.us
mail.stevevalenti.us > IP |