Anti-spam protection for Exchange Server

Select or clear the Detect spam checkbox to enable or disable this protection.

Actions to perform on spam messages

Let the message through: The tag Spam will be added to the subject line of the message. This is the default option.
Move the message to...: You will have to specify the email address that the message will be moved to. In addition, the tag Spam will be added to the subject line of the message.
Delete the message
o Flag with SCL (Spam Confidence Level)

SCL (Spam Confidence Level)

The Spam Confidence Level (SCL) is a value from 0 to 9 assigned to a message that indicates the likelihood that the message is spam. A value of 9 indicates a extremely high likelihood that the message is spam. 0 is assigned to messages that are not spam. The SCL value can be used to configure a threshold in Active Directory above which you consider a message to be spam: the solution flags messages with the relevant SCL value and lets them through.

Then, it is the administrator who establishes the action to be taken on the message based on the threshold set in Active Directory.

Allowed/denied addresses and domains

Use the Add, Delete and Clear buttons to configure a list of addresses and domains whose messages will not be scanned by the anti-spam protection (whitelist), or a list of addresses and domains whose messages will always be intercepted and deleted by the protection (blacklist).

Keep in mind the following aspects when configuring these lists:

If a domain is on the blacklist but an address in the domain is on the whitelist, the address will be allowed. However, all other addresses in the domain will be blocked.
If a domain is on the whitelist but an address in the domain is on the blacklist, that address will be blocked. However, all other addresses in the domain will be allowed.
If a domain (e.g.: domain.com) is on the blacklist and one of its subdomains (e.g.: mail1.domain.com) is on the whitelist, the addresses in the subdomain will be allowed. However, all other addresses in the domain or in any other of its subdomains will be blocked.
If a domain is on the whitelist, all subdomains in the domain will also be whitelisted.