Many had this problem when in crisis, one would need to purge the Exchange logs but ended up not doing it for the fact that it would be risky and not safe. One can manually and safely purge the Exchange logs with the below script. Open a command prompt and type the following.
Note: the m: would be your drive where the Exchange Mailbox databases are.
add volume m:
At this moment, nothing will happen and after some time the screen will be populated. As soon as you see the prompt, enter the below.
After some time, you will see the space decreasing and the logs being purged. Although this works on Exchange 2010, it would be the same for Exchange 2007.