I am thinking I know the answer to this but wanted to get Zimbras chime in. The mail store on the Exchange server was at 80gig. As we started importing, we noticed that the amount of data being imported went beyond the 80gig mail store size. Being that Exchange uses SIS (single instance storage) there are many emails that are redundant that only appear once in the Jet DB. I know Zimbra works the same way, however, does it take this into account when importing from Exchange? Or does each mailbox considered independent so email sent to 5 people would appear 5 times in Zimbra since this was an import. I am thinking yes. If so then is there something in place to change this? Our 80gig import is going to take up approx 150gig of space when done.