This isn't new. It's been LinkedIn's practice since approximately forever to get its users to surrender their address books and then to spam [1] every address in them. The fix is simple: block linkedin.com at the MTA. [2] ---rsk [1] It's unsolicited bulk email, therefore spam. We could argue about who's responsible for the spam, and a fair case can be made that those giving up their address books bear some culpability for it...but since it comes from LinkedIn's domain and LinkedIn's mail servers and LinkedIn's network and LinkedIn's software (which is expressly designed to do this very thing), I think it's fair to say that it's LinkedIn's spam. [2] If you don't want to do this on all mail servers, it should definitely be done on those hosting mailing lists, either at the MTA or in the mailing list software's configuration.