Blacklist Method – It is one of the most popular strategies for stopping undesirable mails by blocking the messages from a senders list made by you and the system administrator. This method looks for the records of IP addresses and the location of mails that have earlier used for sending spam. The point when the message arrives at the inbox, the spam channel starts verifying whether the email address or the IP enlisted in the blacklist and if it is there, the message can be considered as spam and is rejected.
Content-Based – Rather implementing different policies for all messages from a particular IP address or mail, the content-based spam filtering techniques assess the expressions or words found in each user’s message for deciding if the mail is spam or it is acceptable.
Bayesian Filtering – It scans the whole context of the mail looking for expressions or words that could display spam. They apply methods like mathematical formulae for dissecting the substance of the message and compare the substance with the records of the account holder’s spam and legitimate messages.
Header Filtering – This spam filtering technique is much more refined where the email headers are evaluated in addition to subject fields, sender and recipients displayed by mail browsers. The header channels check the data chain left by the mail servers ( https://www.securence.com/blog/ ) that were used as a part to convey your mail which is commonly known as the relay chain. As spammers make sure they are not followed, they place false data in this relay chain so that the users can reply to the mail and their location can be traced. The headers also help in identifying the illegal headers, which are a sign that the mails are spam.