Update Rollup 5 for Exchange 2007 fixes the issues that are described in the following articles in the Microsoft Knowledge Base:

940051 (http://support.microsoft.com/kb/ 940051 /) The recipient information in an e-mail message incorrectly contains the character string “%40″ in the address instead of the at sign (@) in Exchange Server 2007

940058 (http://support.microsoft.com/kb/ 940058 /) Non-English characters in the meeting description field are replaced by question marks when an Exchange Server 2007 user opens a meeting invitation that was sent by a Lotus Notes user

Also see relevant KB article here.