Whenever I try to attach items larger than 1 megabyte to an Outlook Web Access (OWA) email and the Symantec Mail Security for Microsoft Exchange (SMSMSE) service is running, OWA returns "500 Internal Server error" instead of displaying the attachment.
File being attached is larger than one (1) megabyte (MB).
If SMSMSE service is stopped then OWA is able to attach files of any size correctly.
Virus Scanning Application Program Interface (VSAPI) debug log shows the following errors:
A timing conflict between two Microsoft processes. When SMSMSE is enabled, it activates a component of the Exchange Information store called Virus Scanning Application Program Interface (VSAPI). Whenever VSAPI is enabled, Exchange places database locks on items as soon as they are loaded into the Information store. Exchange then passes a copy of the item to the SMSMSE scanner for verification that the item is clean. Once a verdict is returned from the SMSMSE scanner, the database lock is removed, and Exchange will once again display the item to clients and allow delivery to it's final destination. When a user attaches an item with OWA, Internet Explorer uses an HTTP POST command to upload the item to the Information store via Internet information services web service (IIS). It then runs an HTTP GET command to build the next page with the item attached. This GET command is run before SMSMSE has had a chance to verify the contents of the item, and thus the item is still database locked by VSAPI. This results in a 500 internal server error instead of the correct page.
Symantec is aware of this issue. At this time the root cause is not identified. If the workaround cannot be used contact Symantec Technical Support to continue troubleshooting.
Install S/MIME controls for Internet explorer. This causes OWA to use methods similar to Outlook clients in uploading attachments bypassing the timing conflict from the HTTP GET command as it is no longer being run.