To determine which messages are SPAM or which are not, set of protocols is being used. There are several different filtering types available:
Header filters - you can find an essential real technical information. In headers, you will find sending/receiving servers, a real date, and sender information.
Blacklist filters - once SPAM message is marked as SPAM, all headers information is sent to the general blacklists. IP blacklists are SPAM blocking lists that many filters are using to block specific systems that have a history of sending SPAM. Before transmitting an email message to the Inbox, sender IP should be checked against over 100 DNS based email blacklists.
Rules-based filters - you can create your own rule to block a specific message. For example, block messages with the word "Cheap Offer!".
Also, you can run all your messages through specific online tools. However, our recommendation is to use a professional SPAM filter that filtering methods are included. SpamExperts offers more than this. SPAM filter is based on self-learning methods, it means that more than all practices are in use. Everyday SPAM filter learning new ways to avoid SPAM messages.