Consider the following scenario:
You send a meeting request to another Microsoft Exchange Server 2010 user.
The user responds to the meeting request as Tentative by using Outlook Web App (OWA).
In this scenario, a space is missing in the subject line of the Tentative response. It shows "Tentative:<subject>" instead of "Tentative: <subject>."
Note This issue does not occur in Microsoft Office Outlook.
To resolve this issue, install the following update rollup:
2579150 Description of Update Rollup 4 for Exchange Server 2010 Service Pack 1
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.