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What is email black list
An Email Blacklist is a database of addresses used by known spammers. Using this information, anti-spam filters installed on mail servers can reduce the amount of spam they process by blocking email messages coming from those addresses. Blacklists are used by thousands of email hosts as one of their main defenses against spammers. In today’s skeptical internet communication environment, a legitimate email system can also end up being blacklisted, resulting in mail delivery problems and immeasurable costs in lost business. According to a study released in August 2006 by Return Path, Inc.’s, Assurance Services division, seventeen per cent (17%) of permission-based email messages get incorrectly blocked or filtered by the top 12 Internet service providers. Even emails addressed to confirmed recipients may never reach their inboxes.
- DNS Blacklists
Domain Name Server (DNS) Black lists are lists of IP addresses that are the source of unsolicited emails. With the help of these types of lists, mail system administrators can block mail sent from “spamming” domains. DNS Blacklists are usually maintained by anti-spam organizations or by individuals. Lists maintained by individuals may not be up-to-date and reliable, particularly those run by anti-spam vigilantes. WebHelps was on such a List for quite some time, for the sole reason that we host our servers with Rackspace and this individual listed all of Rackspace’s customers, whether or not he had any evidence of spam coming from their server(s). - IP Blacklists
IP Blacklists block specific IP addresses (and IP ranges), message senders or message recipients (local mailboxes) as determined in the Blacklists. The problem with using an IP Blacklist is that it may cut off legitimate users trying to access sites or blogs, or prevent them from sending email to users. - Spam Blacklists
Spam Blacklists are lists of mail servers or open relays known to be used by spammers to deliver unwanted email. Mail System administrators can use these Lists to block spam transmitted from such sources. - Email Blacklists
Email Blacklists contain known mail servers and email addresses used by spammers. These lists are not frequently used by mail system administrators because of the high probability that legitimate mail is also being blocked. - IP blockers & IP Blackholes
IP Black Hole lists are large repositories of IP addresses that are known to be spamming. These repositories use various reporting mechanisms ranging from human reporting to spam-trap email boxes to determine who is sending spam, and when a spammer is identified by IP or IP block, the spammer is added to the Black Hole list. ISPs and email providers can configure their email servers to query the Black Hole list any time a new email comes in. When a new mail arrives at the server, prior to putting it into the recipient’s mailbox, the server will examine the email, and trace its origin. Then it will ask the Black Hole list if this email came from a source that is a currently-know spammer. If the email does not originate from a source known to be spamming, it will be properly delivered into the recipient’s email box. If the mail fails the test and is flagged as spam, the email will not be delivered, but rather will be moved to a storage box for future examination by either the mail system administrator or the recipient.
Related posts:
- Error codes in email
- Server-side spam protection using RBLs (Realtime Blackhole Lists)
- Yahoo guidelines for email security
- Evolution of spamming
- Image spamming
- Pdf spamming
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