Zoominfo, DiscoverOrg, and Lead411 are popular lead generation sources. Every once in a while someone comes along and tries to defend the use of crowd sourced list generation services (of which ZoomInfo and Jigsaw seem to be the largest). These systems work by allowing people to download contact information for third parties in exchange for the requester uploading contact information for other people that they have. Some will also use programs which will search the Internet for information which can be used to locate contact information.
The accuracy of these systems leaves a lot to be desired. This domain is an excellent case in point. Back in 2012, I noticed a series of “verification” notices from Zoominfo. These notices were to addresses which have never existed before and which still do not exist as such today (although the domain does use a catchall system which is reviewed and then feeds mail addressed to non-existent users into a DNSBL). After some research, I discovered that people had put contact information into Zoominfo for people who had left comments on this blog at various points in the past.
Since then, those addresses have received a lot of mail, all of which can be directly attributed to Zoominfo and its information suppliers. Much of that mail has gone to two addresses in particular. Those addresses receive a mix of marketing messages (Jerrica Lee from Hong Kong Tailors spends a lot of time telling people that the company will be visiting in the San Francisco Bay and Los Angeles areas, for instance) and Nigerian 4-1-9 scams.
None of this means a whole lot in the grand course of the universe, but when people ask why ESPs don’t allow this kind of data, it’s because even “verified” addresses haven’t really been verified. This will cause an increase in complaints and dramatically increases the chances of a blocklisting. Often, policy enforcement and/or Spamhaus SBL mitigation efforts consist of getting clients to let go of bad data and the practices that cause that bad data. A significant portion of the time, it’s discovered that the lists which get people into trouble were originally obtained from these list generation companies.