The antispam engine does not detect spam when the sending server uses authenticated SMTP.
SMSMSE does not scan messages from authenticated SMTP servers.
Upgrade to SMSMSE 6.5.2 or higher.
There are two possible solutions, depending on how Exchange has been set up to bypass these SMTP sessions:
Configure SMSMSE to always scan email coming from authenticated servers
WARNING: It is highly recommend that you back up your system registry before making any changes. Incorrect changes to your registry could result in permanent data loss or corrupted files. Modify only the keys that are specified. See Backing up the Windows registry before proceeding.
1. Open regedit.
2. In the Registry Editor create the following DWORD key:
32 bit systems: HKEY_LOCAL_MACHINE\Software\Symantec\SMSMSE\<version>\Server\Components\SMTP\DoAntiSpamOnAuthSessionsBool 64 bit systems: HKEY_LOCAL_MACHINE\Software\Wow6432Node\Symantec\SMSMSE\<version>\Server\Components\SMTP\DoAntiSpamOnAuthSessionsBool
Where <version> is the version of SMSMSE installed. The following is an example of 6.5 installed on a 64-bit system: