How Blacklists work at Rice
The Office of the Vice Provost for Information Technology (IT) has received numerous requests for relief from the overwhelming volume of junk mail received by Rice community members. One set of services that can help block spam and phishing messages from Rice email customers is called blacklists, or real time blacklists (RTB).
At Rice, using a blacklist service means that the sender's address for every incoming email message is compared to several blacklists and messages are accepted or rejected by the Rice email system based on where the message originated.
Here's how it works inside the hedges:
- Open source organizations use databases to track email servers that send spam messages or that are set up (configured) in such a way that they can be hijacked by spammers or used as a front for spam or phishing agents. These organizations publish suspicious server addresses in blacklists.
- A software application protecting the Rice email system compares the sender address on all incoming email messages to addresses on the blacklists.
- When an inbound email originates from an email server found on multiple blacklists, Rice refuses to accept the incoming message and returns it to the sender with an explanation of why it was blocked.
- Alldepts, pres-fac, and other Rice-originated email messages do not go through the blacklist service because the messages originate within the Rice system and not outside of Rice.
- Spam identification tools such as DSPAM and Spam Assassin continue to rate the content of messages within the Rice system, placing ***SPAM*** tags on messages that have a high probability of containing junk mail. These tools cannot stop the delivery of messages and are not connected to the black list service in any way.
The following illustrations show several examples of how messages sent to Rice are managed when a blacklist service is utilized.
Click anywhere on the image for a larger, printable version.
Can a legitimate mail server get off a blacklist?
When a client on an blacklisted mail server receives mail rejection notice due to a blacklist reference, the administrator can correct their servers' configuration and then work with the blacklist manager to remove this server from their list.
For more information on RBLs, see DNI's explanation at:
http://www.dynamicnet.net/news/articles/understanding_how_rbl_work.html
