As an out of state owner of multiple investment properties, I suggest you avoid using the lists of non resident owners. In my opinion, direct mail is a waste of money because every owner is getting multiple mailings. I get from one to 10 solicitations to buy my properties a day. Straight to the recycle bin. The most successful off-market buyers walk their neighborhoods of interest. They chat with people and note the addresses of houses that are run down or appear to be unoccupied. They get information from people in the neighborhood about these properties and research contact information, particularly phone numbers. They call these owners and inquire politely if they are thinking about selling. No pitch of I'm prepared to make you a FAIR CASH OFFER, which doesn't work. If there is interest, they try to get in to see the property and have a low key conversation. If it works out, great, if not, on to the next one and maybe the motivation of this owner will change.
I had one of those people hit me up for one of my properties. The house was vacant and we were getting ready to put a new roof on and paint the exterior. I'm sure he saw it was vacant and noted the old roof and paint before he decided to call. I cut him off, telling him I was also an investor and the house was going to be renovated. We chatted and hung up. Several months later I saw the house around the corner being trashed out. I looked it up in the tax records and he had bought it at a very good price, given how fast prices were rising.
A good investor agent also owns rental properties. That's good and bad. If they spot a really good deal. they might buy it themselves. Success for the best investor agents means they make good money on their properties and on feeding you deals. You make them happy by buying consistently and by giving them both the buy and the sell transactions if it's a flip.
I don't frequent Bigger Pockets these days. Too many sharks and charlatans.