Know more about the several components offered by ERS.
Below are the features of ERS:
- Real-Time Blackhole List (RBL+) Service
In this service, a single DNS query is sent to the RBL+ database, which contains documented sources of spam and list of dynamic IP addresses. If the sender is included in this database, your mail server will return a '550' error or reject the connection.
- Network Anti-Spam Service (NAS)
This feature includes the Dynamic Real-Time Spam Blocking. If the first query to the RBL+ database does not return a positive response, a second query is sent to the QIL database. In this case, a positive response returns a '450' error or a temporary failure of the requested connection. This database may occasionally list legitimate mail servers with compromised hosts behind them that are temporarily sending spam. If this is the case, it will re-queue and try again later, causing a delay in mail delivery until the listing expires.
For more information about ERS, refer to the ERS Online Help.