mailing vacant properties

[Mike Goikhberg]

Here's my question to anyone who may have gone through this process - I got a list of all the properties with tax liens on them in Baltimore city, that will be going up for tax sale soon in 2017. I also got a list of all active code violation properties from the housing department. Both lists designate if the addresses are vacant or not. So, should I just mail all the NON vacant ones, since the vacant properties often may not have address forwarding set up? Has anyone had experience with this as far as how much return mail you get when mailing vacant addresses? I want to pull 200 addresses in zip codes relevant to where I'm looking from each list, I just want to decide whether to target vacant properties or not. I know there is a service called spyreal.com which can really help find the right addresses to mail for the vacant properties but they charge like $200 to analyze 30 addresses...and that's obviously way too much considering I'm trying to amass 400 addresses. Any and all input appreciated!