The company, which works for more than 550 clients including Argos and Samsung, plans to use the money to launch additional products and services in the marketing technology arena.
Jonathan Meeks, a managing director of the private equity firm TA Associates is to join the board of eCircle which, he said, had become "the cross-border leader in a fragmented European market".
Meeks said: "This unique position makes eCircle the ideal platform for a future truly integrated online marketing service company."
The email company is headquartered in Munich, with more than 200 employees in Germany, the UK, France and Italy. Its 2008 turnover was £22.2m.