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Spamming refers to sending unsolicited messages through electronic messaging systems. Besides consuming the corporate email bandwidth, unwanted or unsolicited emails also negatively impact employee productivity. Enterprises will thus have to keep the spamming problem in check. If this is not done, then spam can indeed result in a number of problems.

The problem of receiving an increasing number of unrequested and unwanted emails has reduced to a large extent over the past 15 years. Antispam forces, until recently, assumed that there was no way to catch an adequate number of unwanted emails to bring about a difference. With anti-spam software becoming increasingly popular, the wave of spam has indeed slowed down.

Working of a Coordinated Anti-spam Effort

ISPs and Spam

Anti-spam protection for a regular computer commences with an Internet Service Provider (ISP) such as AT&T, Cox Cable, etc. They use refined software on their email servers to instantly catch spam, thus attempting to prevent the spam from ever reaching the individual.

Anti-spam software is included by several ISPs offering email accounts for their users. However, it is not as robust as that needed by individuals. This is where anti-spam software plays a major role. This software functions from the email program, whether that is Outlook, Gmail, or various other programs. With anti-spam software, emails that have suspicious content are flagged and then immediately sent into a spam folder, instead of going into the regular inbox. These emails are thus set aside for later investigation.

Content Filtering

Content filtering is an approach in which anti-spam software analyzes an email’s subject line and body along with the words contained in a message. The headline is examined against a wide internal database of terms and words used by spammers. Some of the most obvious terms or words include:

  • Millionaire
  • Free
  • Extra cash
  • Rolex discounts

Anti-spam software plays a vital role in this approach by altering the spelling of words and employing several other tricks to prevent getting blocked so that they will be able to sneak their messages to the user. Content filters, on the other hand, just block emails containing flagged, “spammy” words, word phrases and word combinations.

Bayesian Filtering

A Bayesian spam filter is a more sophisticated and highly complex approach used for detecting spam. While analyzing an email, this filter calculates the probability of that message that is being spammed and then grades its “spamicity”. That specific message and word will be flagged as spam if the spamicity exceeds a threshold. Furthermore, the Bayesian spam filter is also capable of building a custom database by learning to choose words that are considered to be spam and those that do not fall under the spam category. This selection is based on words selected by email customers. Frequently used in the open source community, this method is capable of filtering more than 99% of unwanted messages.


The IP address of the spam sender’s computer is first identified by a real-time blacklist, and this is followed by advising its subscribers’ ISPs to block emails sent from that address. This method is considered to be extremely effective, however it inevitably leads to a cat-and-mouse game between blockers and spammers – and it could also be possible for legit messages to get bounced sometimes.


Heuristic analysis software searches for bugs, invalid message IDs, and various other telltale spam traits. It then develops a numerical score for every single email that comes in. The email gets blocked if the score hits a designated limit. At times, authorized messages also get velvet-roped.


Labeling allows senders to just mark messages as spam or legit. Labeling of spam by senders is an existing requirement by more than 25 states.


Distributed identification allows a community of peer-to-peer users to flag spam for one another. Once adequate recipients object to a specific message, it then gets automatically transferred to everyone’s spam folders. This approach was pioneered by SpamNet, an Outlook add-on from Cloudmark of San Francisco.

Learn how you can eliminate spam from accessing your end-users here:

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