I though they host their mail servers in a different data center.
They own SpotVPS, both sites are in the same data center (HostDime).
Edit: I contacted SpotVPS and they said that they're working on this issue.
I'm glad you have had such a good experience.
I used FtpIt for 2 months and have had an amazing experience with them. I cancelled my VPS because I had no use for it, I'll be sure to order again when I need one.