Mimecast, a startup that offers a email archiving, continuity, and security software has raised $21 million in Series B financing from Index Ventures and Dawn Capital.

Founded in the UK in 2003 by Peter Bauer and Neil Murray, Mimecast’s cloud based platform extends the capabilities of most in-house email systems by integrating additional storage, archiving, and spam/virus protection. For example, the software could exchange the value of Microsoft Outlook’s email platforms. Mimecast currently has close to 2,500 customers across a range of of industries including financial services, legal, manufacturing and the public sector. The startup claims to have seen triple digit revenue growth in each of the last three years.