Modify
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\Server name\Private-Mailbox Store GUID
and
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\Server name\Public-Public Store GUID
Source: Techarena
Category Archives: Exchange 2003
Error 0x80070057 creating Outlook 2010 Profile
Auto setup fails with Error 0x80070057 creating Outlook 2010 Profile connected to Exchange 2003 server.
Install Hotfix available here: Outlook 2010 Hotfix August 31 2010
Source: Microsoft
Exchange 2003 Increase max message size
The default is 10MB.
To increase:
Exchange System Manager > Global Settings > Message Delivery > Defaults
Here you can set sending message size, receiving message size and max number of recipients.