Hello,
Another great post from the Exchange Team Blog that is really worth reading :
Troubleshooting Rapid Growth in Databases and Transaction Log Files in Exchange Server 2007 and 2010 - Exchange Team Blog - Site Home - TechNet Blogs
http://blogs.technet.com/b/exchange/archive/2013/04/18/troubleshooting-rapid-growth-in-databases-and-transaction-log-files-in-exchange-server-2007-and-2010.aspx
Kindest regards,
João Ribeiro