Challenge–response spam filtering
Challenge-response spam filtering is like playing a game. When you play a game, someone might ask you a question or give you a task to do. You have to complete the task or answer the question before you can continue playing the game.
In challenge-response spam filtering, your email account is like the player and the task is to prove that you are not a robot sending spam (unwanted or irrelevant messages). When you receive an email from someone who is not already in your contact list, your email account sends a challenge message back to their email address.
The challenge message is like a question that only a human can answer. For example, it might say, "please type out the word 'banana'". The person who sent the email has to complete the task and reply with the correct answer (which is banana).
If the person responds correctly, their email is added to your contact list and their future messages will go straight to your inbox. If they do not respond correctly, their email will not go through and will be considered spam.
This method of filtering out spam helps to protect your email account from getting overloaded with unwanted messages and makes sure that only real human beings are sending you emails.
In challenge-response spam filtering, your email account is like the player and the task is to prove that you are not a robot sending spam (unwanted or irrelevant messages). When you receive an email from someone who is not already in your contact list, your email account sends a challenge message back to their email address.
The challenge message is like a question that only a human can answer. For example, it might say, "please type out the word 'banana'". The person who sent the email has to complete the task and reply with the correct answer (which is banana).
If the person responds correctly, their email is added to your contact list and their future messages will go straight to your inbox. If they do not respond correctly, their email will not go through and will be considered spam.
This method of filtering out spam helps to protect your email account from getting overloaded with unwanted messages and makes sure that only real human beings are sending you emails.