And if I can sign a contract.

I suspect the market to take a turn during the next reelection (Ray Dalio and alot of PE firms suspect the same if not sooner) and plan to purchase alot of properties and lots subject-to on the coast.

I signed a purchase agreement today.

Too many turns to list here.

Is this a turn-key property or require rehab?

And for the wholesalers out there, we unfortunately turn clients away from many deals because they're too tight (even with our lower end pricing).

As long as hes been a reasonably good tenant and there’s nothing that makes you think he’s trying to turn this into unpaid tenancy, agree.

I'm currently planning on hand addressing all envelopes (my list is about 400 properties, starting small) and signing all the letters.

Does it actually work and increase profits without turning off potential guest? 

If you're suggesting he pull equity out of current residence, use it as a downpayment on new residence, and turn current residence into a long-term rental, that's a valid strategy, however he would have to evaluate ROI on the potential rental, and be able to qualify for the loan on new residence with a higher DTI ratio.