According to our contract I have 20 days to write a letter with the defective issues I have found (inspectors write up).

The second buyer hasn't paid any real estate taxes, the water bill, or insurance since he took over, so I had to deal with those phone calls and letters, but the extra income was definitely worth it in my opinion.  

Just received a letter from my mortgage bank that my current FHA loan is eligible for an FHA Streamline Program.

Chicago is very block-by-block so some of my properties were overrated and some underrated.

@Galaxy GavinI believer DealMachine has a feature for this and does ballpoint pen letters as well but I’m not sure the cost and the accuracy you can pinpoint to

Pre-approval letter with a lender will be great specially if you are looking to buy distress properties and asking for a superstar agent. 

Even then, in my experience, zoning violation usually get dealt with through a letter from city hall giving you 30 days to comply.

I'm strongly considering taking one of my pre-foreclosure letters and customizing it for HOA delinquency and sending that. 

Give them a clear letter of non-renewal. 

And then I would surprise my tenant with something nice for them, thank you letter and gift certificate for dinner, something just to say thanks for working through things to assure on-time rent payments (yes, VERY good business, it's called CONDITIONING).