My employer has recently moved from Novell GroupWise 6.5 to Exchange 2010. We've imposed mailbox limits on staff but we still need to move their old messages, contacts, calendars, etc. over to Outlook 2010.

Our problem however is this, utilizing the Novell MAPI client is slow within Outlook 2010 and upon exporting messages to a PST file (for later re-attachment, and offline backup purposes) crashes the GroupWise server. Connecting to the server in Outlook via IMAP to export messages to PST is faster and apparently more stable but also crashes the server.

We'll be keeping our GroupWise server online internally until then end of the year but I have staff with mailboxes approaching 12 gigabytes, which is fine if we're going to move the data to offline storage (DVD set) but if I keep crashing the server every time I try to get the data I'll just be spinning my wheels. In my first attempts, I tried to move mail for a staff member with 3GB of data. The transfer lasted roughly 8 hours before crashing.

I'm wondering if there is an open source solution to my problem. Paid solutions exist but we're a not-for-profit organization and have too many staff to justify the costs of per seat licenses just to migrate mail.