I’ve sent my share of unsolisited email, and had some pretty decent results to tell the truth. When I started LOH I used yahoo groups invite feature .. searched yahoo member profiles for females with the word holdem in their profiles.. when they asked me how I found them I didn’t lie, I just told them, i did a yahoo search.. I am sure there are those that just deleted the invite without reading, thats what I normally do 
.. but there were also a couple hundred that joined the group, and quite a few that played and still have valid accounts.
Of course that was a pretty specific niche.. so ymmv.. but.. more recently, I started another site, and did buy an email list.. I don’t plan to go into any details, but I have seen some results, not as many as before, but some.
~LadyH