@Mark Cohen
It is strictly a numbers game and I would expect very low results with simply a generic absentee owner list. To be honest, I get about half a dozen postcards and letters every week on my properties and shake my head every time thinking about how someone just wasted time and money on them.
If you want to see better results you either have to send out thousands more mailings or maybe you should refine your list and try to pinpoint the type of owner that may be interested in selling.
Drive some of the list (driving for dollars) and look for ones that are not being taken care of or in need of obvious repair. Focus your efforts on those and you will probably get much better contacts. You could even go the extra effort and send them pictures of the houses tall grass or missing shingles and the owner may not even know they are in such bad shape that they may be more interesting in selling quickly. I would rather send out 50 specific mailers on problem properties than 1000 generic letters that no one will really read.
If driving and looking is too much effort then I would look for another way to find deals. Houses won't just fall in your lap, you have to go find them.