I signed up for the free 30 day trial of qbo last night and I saw the option to import your desktop file.

Not many people IRL care to hear about your real estate adventures, trials and tribulations so it's awesome to have a forum like this where people not only listen to what you have to say but are genuinely interested as well. 

I will try to grab the copy of what we used on our last mailing off vista, but I plan to do another 5-6 mailings and I'm sure I will stumble upon what works best from trial and error.

@Jason Turo I can't say we actually "tested" anything (more trial and error) but we did talk to our best buyers to ask them what counties, zip codes and neighborhoods we were interested and the prices they would be interested in buying properties in. 

Is it just a trial by error?

As time has expired, you bought this house as-is, and your insurance has a iron-clad trial-tested exclusion.

For example, I recently played around with accounting for variation when modeling property appreciation (a simple metric that I started with).

I recently tried the free trial of https://www.rentometer.com. 

Since there was a tight profit margin as it was, this left little room for any negative variations.

It is up to you though, there are certainly companies out there that own all the .com, .net, .org, .us, .info, etc. variations of their site and some even own misspellings of the site too.