Error Number:0x80040216 when Sending Emails (in CRM)

This is the error that some people have been receiving after upgrading their Exchange 2003 Server to SP1 and using CRM 1.2

Microsoft CRM Platform Error Report:
Error Description:
An unexpected error occurred.

Error Details:
An error occurred attempting to dispatch the email : HTTP
status: 404 Not Found. URL may be invalid

Error Number:
0x80040216

Source File:
D:\mscrm\Build\3017\src\platform\include\proxy\proxyutil.h

Line Number:
47

To rectify the issue go into the properties of the "MSCRMCONNECTOR" virtual directory in IIS6 and manually create a mapping for .srf files to the CRM ISAPI extension. The CRM ISAPI extension is by default located at "C:\Program Files\Microsoft CRM\MSCRMConnector\CrmExIsapi.dll”

Something else you may want to check is to make sure the MSCRMCONNECTOR directory is not set to require SSL. There should be an event log error being written in the CRM server when e-mail submissions fail. This may also provide clues to the problem.

Finally ensure that the website is started.