How email service providers tag spam

Updated from original posted on http://castechbytes.blogspot.com/2009/09/how-email-service-providers-tag-spam.html

As a former technical support representative for an Internet Service Provider (ISP) in the United States, I have come to understand how their mail servers work in reducing spam. Of course, the one I would like to discuss is just the basic manner of recognizing spam. Providers may have other means of identifying spam.

First: Let's have a working definition of "spam" as unsolicited email--be it business, advocacy or commercial email. I will not talk about IM spam or spam in other internet-based communication channels.

Identifying Spam

Spam identification is the key to spam reduction, so most email service providers actually focus on that aspect. As soon as they determine that an email is spam, what they do with that it is just a matter of creativity on the email address owner or the email service provider.

There are two key strategies in spam identification: Keyword monitoring and Spam tagging.

Keyword monitoring is (of course) monitoring key words in the email's subject line. Based on the ISP's pre-studied list of words that are most likely to contain spam, ISPs control the distribution of messages that have these words. Instead of going to the recipients' Inbox, they go to the Junk or Bulk mail folder.

This means that if you send email with words such as "tits" or "dicks" in your email, this will probably be sent to the Spam folder of the recipient if the email server has that approach in spam detection.

While this seems logical, the downside of this is not supported by certain groups as this same rule may be applied to the words such as "breasts" or "penis" which may be required in medical professions. Useful emails may be forwarded to the spam folder without knowledge of the recipient (obviously) even though they intend to receive it.

Spam tagging refers to the use of the "Report Spam" or "This is spam" feature of your email service provider to report that the email you are reading is actually a spam. Most of the email service providers have this feature, but the level of effect of the feature varies.

With this feature, what happens usually is that the email you use is transferred to your Spam folder. What you may not know, however, is that what you actually do is not just tag the email as spam, but tag the sender as a spammer.

This indicates that if a certain number of users tag that email sender as a spammer, the email server of the recipient will automatically tag it as spam, resulting to the future emails of that sender to be forwarded to the Spam folder, even for other receivers.

Of course, these days, a combination of the two, together with artificial intelligence, is used to identify spam.

Cost of Spam to Organizations

Spam costs a lot of money for organizations as they have to deal with wasted resources (bandwidth) and time (for deleting spam), not to mention privacy and other security issues, so proper identification of spam is important. Estimates in 2012 indicate that spam costs internet users globally about $20 billion to $50 billion. On other hand, you should be careful with tagging an email as "spam" if you are in an organization where the sender is sending relevant information that only you do not appreciate receiving. You may be costing the inconvenience not only to the sender but also to the other recipients.

If you discover that you  received an email but it is in the Spam folder when it is actually not spam, you can do any of the following:

1. Use the "Unmark as spam" or similar feature
2. Add the recipient's email address to your address book. This adds a rule to your email that the sender is a valid contact.