We all hate spam. It isn’t just that we get a bunch of unwanted emails trying to sell us misspelled pharmaceuticals or low, triple-digit interest rates. But it is also the fact we have to deal with legitimate emails falling into our spam folder. How does our email decide what should go to your inbox and what should be banished to the spam folder?
Most modern email systems use an algorithm to classify spam. This algorithm varies by email provider but the variables tend to be the same. Some corporate email boxes can even be configured by an IT department. But of course the exact rules and weights of each algorithm are not made public as no one wants spammers cheating the system. Let us take a look at a few common ones.
First of all, is the email address one that you have interacted with before. Interacting with an email by clicking links or sending a reply will often signal to your email provider that this email address is legit. Having that email address saved as part of your contacts is an even stronger signal that you want to receive email from that address.
If you mark an email as spam, even accidentally, then your inbox will most likely automatically send any email from that address to the spam folder. This is important to check if you are having an issue with a legitimate email address always ending up in spam. You can often fix this by explicitly marking the email in spam as "not spam."
Along a similar route, if you never open an email from a certain address, your inbox may eventually assume that it is spam. In some cases this is the correct thing for your email to do. However, I have had issues more than once with my Gmail believing certain emails were spam simply because I delete them without ever opening them. I do this to many emails that are mainly notifications and contain all the information I need in the subject line.
Additionally, your email provider looks at the history that the email provider has had with that email address. Has someone else marked this email as spam before? Does this email address frequently send bulk email? Reputation of an email address is often tied to two different sources. One is the domain, that is the address after the @ symbol. The other is the IP address which is a unique identifier for the server that is sending the email. Even the length of time that domain or IP address has been owned by the sender will be used.
There are also some more technical aspects that the spam algorithms look into. There are ways of spoofing an email address so your mailbox always tries to authenticate that the address listed as the sender is truly the real sender. Mismatched identifiers is a great way for a message to be sent to spam.
We will probably always live with spam. The algorithms will continue to get smarter but so will spammers. Good emails will sometimes get caught into spam while real spam will sometimes slip through the cracks. However, having a little knowledge about how spam filters work can lessen the stress of dealing with spam.
Brian Boyer is the managing partner of Web Pyro (http://?www.webpyro.com) located in Wooster.