Microsoft Exchange Server 2007 Search is a feature that enables you to quickly search text in messages by using prebuilt indexes. The Exchange Server 2007 Mailbox server maintains a set of filters that are used to read attachments and index the data in them. If there is no filter installed for a specific attachment type, Exchange Server 2007 skips this type attachment but still index the message. However, Exchange Server 2007 cannot index a message when the following conditions are true:
There is a filter installed for a specific attachment type.
An attachment of this specific type does not contain the expected type of contents.
Additionally, this attachment does not get indexed. For example, certain third-party programs will generate .xls files that are not real Microsoft Office Excel workbooks. However, Microsoft Office IFilter requires real Excel workbooks. Therefore, messages that have such type of .xls attachments do not get indexed.
To resolve this problem, install the following update rollup:
2407025 Description of Update Rollup 2 for Exchange Server 2007 Service Pack 3
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about Microsoft Office IFilter, visit the following Microsoft website: