The Heluna spam filters work based upon the idea of "sensitivity". Each user has a sensitivity setting assigned to them, and if an email's test rating exceeds that sensitivity, the email gets marked as spam. Site administrators can set a default sensitivity level for the domain with the option to customize it on a per user basis.
To generate an email's test rating, each email bound for your domain spends a brief period going through testing on the Heluna servers. Upon completion of testing, a message’s score is compared to the recipient’s sensitivity rating in order to designate the message as spam, possibly spam or definitely spam. The tests that messages go through include:
...along with many more tests which are constantly being improved by Heluna.
Each user has the ability to add email addresses to an approved senders list and to a blocked senders list. Messages from approved senders bypass the filters and are immediately delivered while messages from a sender on the blocked list are instantly discarded. Domain administrators have the power to add email addresses to a domain-wide approved or blocked senders list.
Heluna learns from the emails that are sent to your domain. Senders with a clean history are more likely to have their messages marked as clean, while those who have a demonstrated tendency to send spam are more closely scrutinized.
When a message gets marked as "definitely spam", one of two actions is taken, based on a user's preference. The email can be silently discarded, or it can be placed inside a temporary quarantine. The quarantine exists on the Heluna cloud, and can be accessed at any time. Messages inside the quarantine can be removed immediately, sent on to the recipient or left alone (in which case the message will be automatically removed after 30 days).
Most antispam solutions require a "training period" during which the system is learning to identify spam. This can be an inconvenience as it requires your users to spend time filtering out their own spam. Fortunately, Heluna does away with all of this by supplying a fully-trained filter to clients on day one.
For messages which fall into the category of "possibly spam", Heluna delivers the messages with a warning attached. This warning informs the user that this message may be spam and contains instructions on how to deal with it if it is truly spam.