MailChimp has said that they believe that they have terminated all accounts that were responsible for this. BUT, they say, this is a group that keeps cropping up (think whack-a-mole), so to please report any more of these that anyone receives.
Anne Anne P. Mitchell, Attorney at Law Author: Section 6 of the CAN-SPAM Act of 2003 (the Federal anti-spam law) Legislative Consultant CEO/President, Institute for Social Internet Public Policy Legal Counsel: The CyberGreen Institute Member, Cal. Bar Cyberspace Law Committee Member, Colorado Cyber Committee Member, Elevations Credit Union Member Council Member, Board of Directors, Asilomar Microcomputer Workshop Ret. Professor of Law, Lincoln Law School of San Jose Ret. Chair, Asilomar Microcomputer Workshop
