You're kinda right. MINS is not a database of e-newsletter content but rather a database that describes e-newsletters. This is what all the agencies use to find out where to place ads. They look at MINS then contact the publisher. They tell the publisher they have an advertiser and what is to be advertised. The publisher then agrees to it or not. If they do then the final e-newsletter is sent back to the agency for advertiser approval. It is only at this point of acceptance that the e-newsletter can be sent out. Once everyone agrees to everything. That what I mean by industry standards and if Google chooses to ignore them. If they follow the standards then it is a good option.
But like I also said before, this has been around for a number of years and not really accepted as the first choice. It is because of folks like MINS that enable the e-newsletter publishers to get top dollar for a full e-newsletter sponsorship. It is extremely hard to get an e-newsletter publisher to accept anything but a cpm deal.