The technical uplifts mandates for Exchange administrators to upgrade Exchange server version. Even after a successful upgrade, still database mounting issues persists when Exchange database is corrupted.
If EDB is dumped over HDD or backed-up inproperly then it causes problems to export mail from exchange 2003 to 2010. Thus requires substitute to export exchange 2003 mailbox to exchange 2010.
Recommended Way - Convert EDB 2003 to Exchange 2010 via PST Files
Most reliable method & only way for moving Exchange 2003 to Exchange 2010 is importing PST file to Exchange 2010. Efficiently extract entire data from old server to new server.
The manual way to import exchange 2003 edb to exchange 2010 might not be successful every time. At point of failure, offline EDB file to PST file conversion using software is the trustworthy way-out to extract exchange 2003 mailbox without misplacing a single data bit and import PST files into Exchange 2010 server.
Freeware edition of the software is limited to convert EDB file 15 items per user mailbox. But full version of the software does not have any restriction. Pay $299 for full version of Exchange 2003 to Exchange 2010 EDB conversion software.