Have you ever had the experience of sending an email to a friend or co-worker, only to get an email a few minutes later asking you to click a link or type in some numbers? It certainly can be frutrating for the person who has to do it but did you ever wonder why that happens?
The person that you sent an email to is using a system known as a challenger response system. What this system is set up to do is to make what is known as a white list of acceptable senders of emails. It assumes that spammers do not have a verifiable email address and therefore will not get the email to verify the address and put them on the white list.
Challenger response systems are great for people who have a very limited email list or who do not want any type of spam at all in their email box. However with all spam filtration systems there are some major drawbacks to using this type of spam protection.
First is the problem if one challenger response system meets another one. There is no way for one to respond to the other and be put on the whitelist of acceptable email senders. This can prevent email communications from flowing should one person forget to add the other to their system when they first make email contact with each other.
The second issue is that of mailing lists and other emails. Mailing lists that you sign up for are wanted email ads that you have opt-ed into. None of these lists have the ability to verify that they are a real email address and be put on the white list. You could ultimately be missing out on important email communication if you do not put any of these lists or senders on the white lists.