Tell them they should use their free cell phone to call the ObamaCare customer service line... as you hand them the 3 day to pay rent or quit. 

Nowadays I can look up the owner online then typically use Facebook or other site to send them a message or even get their cell number.I see 4 primary ways to contact:Knock on their doorMail a letterPhone callOnline message (Facebook, etc)I imagine the conversation or note saying something like "Hi, I am a real estate investor looking to buy properties in your area and I noticed that your home is listed for sale.  

Things can happen, but everyone has cell phones, so if there's no word within that window, I leave.

Prime first with an oil based primer to seal the edges (use the low odor oil based unless you wish to have less brain cells when you finish; the regular stuff has a strong odor that will leave you loopy without adequate ventilation). 

That list then goes to the Skip Tracer who combs the internet to find the owners contact info (Cell or Personal home phone).

I have been approached by a cell tower company to put a cell tower on some property.

Please Call Me at(MY CELL)PLEASE CALL!

if it was my own house - nothing better than the closed cell insulation.  

Treat your inexperience just as you did your cell phone time... once you know what the problem is work it backwards. 

This was the 80's before cell phones.