The deal, scheduled to close this month, furthers Chicago-based YesMail's strategy to broaden its services to include stronger customer-retention tools in addition to its existing customer-acquisition capabilities.
YesMail plans to extend job offers to most of Post's 75 employees.
YesMail paid $2 million for the assets of the E-mail Marketing Group, which 18 months ago was valued at $380 million, according to a YesMail spokeswoman.
In October, online loyalty company Netcentives, San Francisco, filed for chapter 11 bankruptcy protection and announced plans to auction off its assets. At that time, it entered into an agreement to sell the e-mail division to Plum Acquisition Corp., but the deal fell through when Hans Peter Brondmo, the head of Plum and founder of Post Communications, accepted a position at Digital Impact
Netcentives' financial woes began last year, forcing it to make several rounds of layoffs and initiate other cost-saving plans. In September it was delisted from the Nasdaq for failing to meet the $1 mininum stock-price requirement.