Who/what is RESMAIL?

There's somebody sneaky in my Gmail spam folder. Some company I've never heard of, apparently called RESMAIL, keeps showing up there, once or twice a week. The footer always says "RESMAIL - 63 Madison Ave 9th Floor - New York, NY 10016 US." The source IP addresses have varied over the past months -- from 173.244.163.182, 66.151.5.167 and most recently 98.126.20.140. They seem to be trying to advertise some semi-legitimate stuff -- Columbia University's School of General Studies, a NY Real Estate Expo, hotels in the New York area, etc. Seems legitimate, except for the fact that I never signed up for it and it's pure unwanted third-party advertising. I'm not even sure how they came to be in possession of that Gmail address -- the only other unwanted mail this account gets is the typical Russian pill and gambling stuff.

Anybody else out there familiar with RESMAIL?