Return receipt and Symantec Mail Security 7.5

Hi all,

I hava a Domino 8.0.2 server with Symantec Mail Security 7.5 with premium antispam enabled.

On Lotus Domino I have International MIME Settings Enabled and Return Receipt Enabled.

Incoming internet messages marked with return receipt, when delivered to Notes Mail Database, seem to loose return receipt property.

I think Domino configuration is ok (on other servers with the same configuration but without mail security it works).

Is there a problem with Symantec Mail Security configuration?

Thanks in advance.

Alessandro