Exchange Backups - Does it include whitespace?

Hi There,

 

We are doing backups of an exchange database with the Symantec Exchange agent.

There is approximately 100gb of white space in the database (1.3TB total). The client is trying to reduce their backup footprint so wants to bring the DB offline to do a full offline defrag to clear this space.

I personally don't think it's worthwhile, but what I'm trying to find out is whether or not the backup using the exchange agent, will actually include whitespace or not?

I'm assuming not since it's not flat file / block level, but need to clarify if possible.

Thanks.