Keeping OST Data during Server Migration

Exchange Server database mailboxes are often migrated to upgrade the existing version of Microsoft Exchange Server or to change the Exchange Server domain. However, this practice can cause serious data loss at the client end, if they are using Outlook with cached mode turned on with no backup of OST data. An Exchange mailbox contains important metadata called .ost encryption key, which is also placed in MAPI (Messaging Application Programming Interface) profile of client computer. During migration, if this key is lost from both the locations, .ost file becomes unreadable. Microsoft Outlook can directly access the .ost file data only when it exists in .pst file format. A Convert OST to PST utility comes handy when you need to convert an orphaned OST by Exchange Server to Outlook-usable PST file.

For more understanding on the concept, consider a realistic situation when an Exchange Server administrator migrates from original server to another with few of its clients having cached mode turned on. When the mailbox migration is completed, the end users want their .ost file data back in readable format.

Explanation

An Outlook user can get access to its .ost file data until the MAPI profile has not been changed. When a client tries to connect to Exchange Server in Online mode, the encryption key in MAPI profile is compared against the key placed in mailbox of Information Store database. If due to any reason, these keys differ, Information Store overwrites the key of client end and thus a new .ost file is created.

In this specific case of server migration, Information Store has been reset. In such situations, new offline keys are generated for each mailbox and won't allow the old .ost files to have a successful synchronization with Exchange Server. So until the profile, in which the old .ost file was created, exists, you can use it to synchronize with Exchange Server and retrieve its data.

However, the best practice before server migration should be to extract all the .ost file data to readable .pst otherwise, it will create Convert OST needs. Convert OST to PST is feasible using third-party utilities, which are available in market for this specific purpose.

Stellar Phoenix Mailbox Exchange Desktop ( http://wwww.convert-ost-pst.com> is a high-end tool that can convert an orphaned or inaccessible .ost file to readable .pst file. This Convert OST utility supports MS Outlook 2007, 2003, 2002, and 2000 and can restore all e-mails, notes, calendars, contacts, etc.