The BNT Mail server uses software that assigns a score to each email that is passing through it. A spam email is one that gets a high score while a ham email (a non-spam email,) is one that gets a lower score. In fact, that's the main distinction.
The software that scans the email is able to pick out some key words and other textual structures that are associated with spam. These text elements, when detected, are given small scores. The highest scores are awarded to email that has been sent from a known spammer.
Contents that can increase the score for an email are:
- Lists of sexual disfunction drugs,
- Short emails containing links to pornography sites,
- Emails that were sent from workstations connected to the internet via dial-up lines,
- Other similarities to emails that people have previously collected out of frustration!
There are two main types of spammers that hit you with annoying spam every day:
- People who send small amounts of email to addresses that they collect from various sources. For example, you might give your email address to somebody who asks for it over the phone. This person might add your email address to a small list that is later sold. The person who buys that list may then combine it with other lists and additional email addresses - then sell the expanded list, too!
- People who send huge amounts of email to addresses that they harvest using automated web bots, generate randomly or collect by advertising bogus mailing lists that they want you to sign-up for.
The main difference between low-volume spammers and high-volume spammers is the number of complaints that are generated. A low-volume spammer might upset you and a few other people in your neighborhood once every day or two. A high-volume spammer will drive millions of people bananas around the world!
If you make enough complaints about the activities of a low-volume spammer, that spammer's information will end-up on an anti-spam list. At that point, the BNT Mail server might be able to give emails from that spammer a higher score - and might have a chance to identify the email as spam and tag it appropriately.
To put it another way: Emails tagged as spam by the BNT Mail server are usually from sources that have generated a number of complaints. Emails sent by low-volume spammers may be just as annoying as those sent by high-volume spammers, but they get a lower score because few people will know about them until you make a complaint. As such, the BNT Mail server may not be able to tag them as spam.
Keep in mind that a low-volume spammer is more likely to remove your email address from his mailing list if you ask him to.