Then, Friday evening my agent sent me the addendum and a letter from the lender (Loan CTC, he called it) stating that the buyer was approved and that his process was now at Quality Control for the green light.

I first attempt a dialogue with the owner, usually beginning with a simple letter of interest.  

As the buyer funds the downpayment, I send a letter of where to mail the next month's rent, the terms of the existing lease are sill enforce and their deposit of $xxx has be transferred to the buyer.

Rest assure there is a good chance the tax collector will be sending you a letter increasing your taxes.  

Perhaps the tenant stored items such as boxes in the corners and the MILDEW (never use that four letter word) was caused by lack of air circulation.Gail

@Chris ChristiansonYou could always apply for an IRS private ruling which is a good idea for questionable transactions. https://www.irs.gov/help-resources/tools-faqs/faqs-for-individuals/frequently-asked-tax-questions-answers/irs-procedures/code-revenue-procedures-regulations-letter-rulings/code-revenue-procedures-regulations-letter-rulings

The deals I buy nowadays tend to be complicated, hairy and/or distressed properties (usually off market) or in one case a result of a yellow letter campaign.  

Here is a contract that works in principle for sellers (Sale and Purchase Agreement)https://www.dropbox.com/s/btdjwte4p8k4j57/Standard...For a lease option assignment, use a letter of intenthttps://www.dropbox.com/s/enf31ammsbt4wfm/Letter-o...that letter of intent has a docusign segment.

In the file are several letters you sent over the years regarding your interest in buying the property.

It really passes the time when I'm working with yellow letters, as I have to hand write them as of now.