How does spam detection work?

We all know spam (unwanted e-mail advertising) is a pestering matter. If you are an e-mail user, it wastes your time. If you are a website owner or a server manager, it takes useful resources from your e-mail server. Those whose work is related to the Internet know that fighting spam is a mouse-and-cat race between its senders and e-mail providers, but we don't usually know how does this spam / anti-spam war works or take place. I thought a short explanation can sort it out.

Spam fighting is, actually, an e-mail filtering technique. This means it uses a technology which is similar to the one which allows you to organize your e-mail in folders automatically. For example, just as you can create a filter in your e-mail software (even with online e-mail software) and ask your computer to store all e-mails coming from, say, your favourite social networking site, in a folder called 'social networks'; anti-spam software use algorithms and calculations to try to filter out genuine from spam e-mail so that it will move spam to a special "junk mail folder" or plainly delete it, according to the user's or server administrator's instructions.

The anti-spam filtering process is not exclusively automatic, though. It trusts the user too. Every user can make a list of e-mail addresses which will always be allowed to send you messages, called a 'white-list', and a list of e-mail addresses which will be always blocked, called a 'black-list'. In addition, every time you flag an incoming message as spam or not-spam, your computer analyses the characteristics of the message you flagged and "learns" from it (figuratively speaking) for future use. This is done to help spam filters become more accurate with your account.

How does a computer calculate whether your e-mail is spam or not, and what can you do to avoid your normal e-mail to be filtered to a junk mail folder? I thought this is an interesting question, and I offer a few guidelines below:

+ First of all, take a fast look at how usual spam looks, and try to avoid those uncomfortable practices. E-mail communications were meant to be personal, so keep your e-mails personal. If you are to send a message to a large group of receivers, then try to set up a mailing list to avoid problems.

+ Next, be honest in your e-mail. Using an e-mail alias is acceptable, but trying to fool computer systems saying you send an e-mail from account A while you are actually sending it from account Z might make you look as a spammer and invite filters to treat you as such.

+ Use standard e-mail software to send your messages. Word processors (for example, Word) will likely include unnecessary code to your messages, making it look like spam. Just use plain text, or, if you are to use HTML e-mails, keep their source code standard.

+ Avoid unnecessary characters, l|ke this 0ne. Spammers use it a lot, so just avoid it.

+ And, if you manage your own domain, do your best to avoid having an open-relay e-mail server, and set up your SPF correctly. Also, use confirmed e-mail addresses inclusion for your mailing lists.

That will keep you covered.


Computers + Online