Heluna Antispam Features

The Heluna spam filters work based upon the idea of "sensitivity", where each user has a sensitivity setting assigned to them, and if an e-mail's test rating exceeds that sensitivity, the e-mail gets marked as spam. Sensitivity can be customized for each user, or a site administrator can set the default sensitivity for the entire domain. Heluna recommends that new clients use the recommended sensitivity (which catches almost all spam messages) before potentially doing unneeded customization.
Intelligent Testing of Each E-Mail

To generate an e-mail's test rating, each e-mail bound for your domain spends one or two seconds going through an enormous amount of tests on the Heluna servers. These tests determine the message's test rating, which when combined with the recipient's sensitivity, mark the message as clean, possibly spam, or definitely spam. The types of tests that messages go through include:

• Valid Recipient - Is this message destined for an existing mailbox?
• Network Address Blocked Lists - Is this message coming from well-known spammers?
• Distributed Message Checksums - Has this message been sent to millions of people?
• Spam Fingerprinting - Does this message include signs of spam software?
• URL Blocked Lists - Does this message include links to well-known spam sites?
• Content Filtering - Is there text in this message that looks like spam?
• Spam OCR - Are there images that contain spam keywords in this message?
• Bayesian Filtering - Does this message look like spam messages we have seen in the past?
• Custom Approved / Blocked Lists - Is the sender of this message always (or never) allowed to send the recipient e-mail?

...amongst many more that are constantly being upgraded and retested by Heluna.

Custom Approved and Blocked Senders

Each user has the ability to add e-mail addresses to a list of approved senders (senders that can always send you e-mail, regardless of how much that message appears to be spam) or to a list of blocked senders (senders that can never send you e-mail). Additionally, domain administrators have the power to add e-mail addresses to a domain-wide approved or blocked senders list, so those senders can always (or never) send e-mail to any user in your domain.

Heluna also automatically maintains its own internal lists of approved and blocked senders for your users, based upon a rating for each e-mail sender that we see. For example, if user@gooddomain.com sends you a few clean messages, Heluna would be more likely to mark future messages from that sender as clean. Conversely, if spammer@baddomain.com sends you a few spam messages, Heluna would grade subsequent messages as more likely to be spam.

Quarantine or Quietly Remove

When a message gets marked as "definitely spam" by Heluna, one of two actions can be taken, based upon a user's preference. The e-mail can be silently discarded, or it can be placed inside a temporary quarantine. This quarantine exists upon the Heluna servers, and can be browsed at anytime. Messages inside the quarantine can be removed immediately, re-sent to the recipient (regardless of how much of a spam message it is) or left alone, in which case the message will be removed in 30 days.

We recommend that users try a test period of having their quarantine disabled, so that messages get immediately discarded. This helps to remove the temptation to go visit your quarantine every day and browse a list of spam messages (which is part of a spammer's goal: to get you to see the title of their message). In the long run, Heluna has found that our clients prefer their daily e-mail when their quarantine is disabled.

Already-Trained Bayesian Filter

Most antispam vendors require a "training period" so that messages can be learned as being either clean or spam. This can be a huge inconvenience, as it requires your users to spend even more of their time going through their spam e-mail. Heluna does away with all of this by offering a fully-trained bayesian filter to new clients on day one. Your setup benefits from our extensive testing, and each message that Heluna has already seen for all of our clients.

Submit New Spam to Heluna

For messages that are marked as "possibly spam" (less than one percent of all messages), Heluna delivers these messages with a message that tells the user that this message may be spam, and instructions to send the message to Heluna if it truly is a spam message. Each submission of new spam to Heluna trains all of our filters even further, resulting in even better performance.