You have Symantec Mail Security for Microsoft Exchange. You want to use a Real-time Blacklist (RBL), also known as a DNS-based Blackhole List (DNSBL), to screen email senders. You need instructions to configure this feature
To configure message rejection with an RBL
Symantec Mail Security for Microsoft Exchange is now configured to use the RBLs that you specified.
You can generate a summary report to track the RBL checks and email rejections.
How to locate RBL (DNSBL) providers
Use any search engine to search for "DNSBL Providers", and you should see a list of blacklist providers. The following are a few examples of DNSBL providers:
How to specify a Real-time Blacklist
You must specify the domain names of DNS-based antispam services to use. Populate the Real-time Blacklist domain name field with the RBL service that you plan to use.
What happens to rejected messages?
If an RBL check matches the IP address of the connecting email server, and the sender or recipient of the email are not in the whitelist, the connection is terminated before the DATA command. The server that initiated the connection receives an SMTP 550 error, which indicates a permanent failure.
The message looks like the following:
"550 5.2.1 Mail from 192.168.247.134 refused: spam site."