Exchange 2003 Service Pack 2 has a new update going out to Microsoft Update and to downlevel WSUS servers. I think it is important to note that client action outlined below must happen to get the new SMIME control to the client's machine. There will be another update coming out soon (no specific date) that will address the client experience issue by alerting the user that the current SMIME control installed on the client is outdated.
Scott Roberts - Exchange Sustained Engineering
Exchange 2003 SP2 update for S/MIME has been released
An update that applies to the S/MIME control in Microsoft Exchange Server 2003 SP2 has been released to the download center. This update resolves a critical issue in the S/MIME control which can cause crashes when used with Internet Explorer 7.0.
After this Hotfix is applied to the server, end users who have an S/MIME control installed on the client machines need to re-install the control from the Options dialog in OWA.
The update is live at:
The associated KB, 924334 is also live at:
This update has also been released via Microsoft Update as a critical update (pending approval from the folks at Microsoft Update).