DCC 49
DCC | DCC (Distributed Checksum Clearinghouse) is a tool used to identify bulk |
| mail and is based on a number of servers that maintain databases of |
| message checksums. These checksums are derived from numeric values |
| that uniquely identify a message. DCC provides a simple but very |
| effective way to successfully identify spam and control its disposition |
| while updating its database with new spam message types. |
| Mail users and ISPs all over the world submit checksums of all messages |
| received. The database records how many of each message is submitted. |
| If requested, the DCC server can return a count of how many instances of |
| a message have been received. The 3Com Email Firewall uses this count |
| to determine the disposition of a message. |
| A DCC server receives no mail, address, headers, or any similar |
| information, but only the cryptographically secure checksums of such |
| information. A DCC server cannot determine the text or other |
| information that corresponds to the checksums it receives. It only acts as |
| a clearinghouse of counts of checksums computed by clients. |
| You must allow a connection on UDP port 6277 on your network firewall |
| or router to allow communications with a DCC server. If this port is not |
| available, DCC server calls will fail and slow down mail delivery. |
| Select DCC from the Mail Delivery |
| settings. |
■Action — The action can be one of the following:
■Just log: An entry is made in the log and no other action is taken.
■Modify Subject Header: The text specified in Action Data will be inserted into the message subject line.
■Add header: An
