What are the e-mail filters and how do they work

E-mail filters can simply be described as rules for your incoming messages. You can set up different criteria and set desired actions for all messages that match these criteria. Common uses for mail filters include removal of spam. Users might also employ a mail filter to prioritize messages and to sort them into folders based on subject matter or other criteria.

Mail filters can be installed by the user (you can do that via the E-Mail Manager (E-Mail Options > E-Mail Manager) section of your Web Hosting Control Panel. Learn how to set up e-mail filters on the server-side here: How do I set up my own custom e-mail filters?

E-mail filters could also be part of the e-mail program (e-mail client) installed on your computer (e.g. Outlook, Thunderbird, Eudora, etc.). Most e-mail clients nowadays also have an automatic spam filtering function. Internet service providers can also install e-mail filters in their mail transfer agents as a service to all of their customers. Corporations often use them to protect their employees and their information technology assets.

Mail filters have varying degrees of configurability. Sometimes they make decisions based on matching a regular expression. Other times, keywords in the message body are used, or perhaps the e-mail address of the sender of the message. Some more advanced filters, particularly anti-spam filters, use statistical document classification techniques. Image filtering that uses complex image analysis algorithms to detect skin-tones and specific body shapes normally associated with adult-images (pornographic images) can also be used.