I have read about an article titled "New Spamming Tactics" from http://ecommerze.blogspot.com/2007/08/new-spamming-tactics.html.
This article defined that spamming is the flooding of electronic mail systems with “junk e-mail”. Also known as unsolicited bulk messages sent through the electronic messaging systems. One common spam is email spam. Spammers willing to send thousand email or more to get a single response. They use tricks to get you to read their messages by using the “Subject:” line. Usually your email address will not appear in the “To:” line and you will never see the email addresses of other people they sent the messages to.
The spammers now have come out with new spamming tactics which are PDF spam, Piggyback spam and Greeting Card spam.
If you have received an email message containing only a subject line and PDF file attachment, it is likely to be the PDF spam. Spammers started to use PDF spam because most of the users expect spam to be an image or text but not an attachment. Besides that, spam filters can not screen the contents of PDF attachment which will make the messages to be sent easily into your inbox instead of junk-mail.
The email recipients should not open the PDF attachment in the message that does not have text in message area. The email must be deleted immediately.
Piggyback spam is embedded URL links that are completely unrelated to the spam being advertised. It may be asking you to click on a link of websites to view the message properly or to get further information. These links may lead to a downloadable file and if the user has download it, malware or spyware including a key logger and Trojan which will takeover the computer and add it to a botnet may be installed on user’s computer.
Users are advised not to save or download any unknown file.
The spammers have devised email that looked like greeting card but it contains dangerous virus. Usually, the subject line of the inbox informs recipients that they have received a greeting card from a friend, family member or love one. When the link to the website is being clicked, the user’s computer will upload the spyware. Once installed, the spyware begins operate immediately which disable the user’s antivirus software and record all emails being viewed as well as passwords that are being entered. To identify whether the greeting card contains spam or not, it usually uses a generic name instead of real name and also leads the user to download some custom software.
Users should not respond to unsolicited emails and don not click on links in the messages.
WIth the increasing awareness of user, the spammers will be continually try to outsmart the anti-spam software.REMEMBER always be suspicious of emails and you will safe from those spammers. Good luck ^^