https://www.donotcall.gov/

You can block email spam by marking the offending emails as spam.  If you use a email client, you might be able to create a rule to delete certain spam.

A guy named Daniel keeps using various numbers of ours and posting ads online that he's renting out apartments, condos and lofts all over Santa Monica and we get calls all day long!  Its really irritating...

ring ring:  "Hello"
caller: "Hi I'm calling about the apartment for rent"
Me: "Well there seems to be a misunderstanding.  Unless you want to go through screening to see an escort, I can't help you"

LMFAO!  But seriously, its irritating.

I have a similar problem from a provider that I tried to see last week.  I asked to see her 5 hours in advance, but she never got back to me; so when the time came I just texted her that I'll try her next time. Now I'm getting calls all the time and after googling the numbers one is from a tranny provider (WTF) and the other is an 11 digit number (another WTF)