Is it a scam of some kind?

It says after installation:
Your box’s reverse DNS is currently, but it should be [my email]
Is it snooping my emails? I have no idea what and I’ve never set it up!
I need some help getting rid of and some explanations!

It’s the reverse DNS name of the IP provided by your hosting company.
So probably you use this hoster? no?

It’s nothing to be afraid off, ask your hoster if they can change your reverse DNS to your own domain, they can probably help you.