Drugs, pornography and fake watches all feature heavily in the recently published top 10 spam list for 2007.

The BitDefender list is topped by penny stock spam, however, which has made a dramatic reappearance over the past few months.

Stock spam was mostly attachment-based in the first half of the year using images, but was replaced by "experimental" waves of MP3 and PDF spam in the second half of 2007.

Although phishing spam proved to be less prominent over 2007, BitDefender warned against complacency as it causes direct losses to victims. Stolen bank accounts are usually "cleaned out" within hours or days.

Threats to terminate the targeted account are the most common type of phishing spam. In a common variation the customer is asked to enter account information as part of an update to "the banking security app".

Phishing spam is also increasingly sophisticated, featuring credible and well-crafted web forms, although spelling mistakes and a web address different from that of the original bank were still apparent in many cases.

Phishing spam will continue to prevail in 2008 as spammers hone techniques to defeat spam filters and use of SSL authentication to get the all-important " lock icon" look in the victim's browser.

Over 2008 there will be a greater emphasis on diversifying the targets, content and appearance of spam as their creators look for improved returns.

BitDefender also noted the appearance of political spam, a category the company expects to grow dramatically as the US presidential elections draw closer.

BitDefender 2007 Top 10 spam list:

1. Penny stocks spam
2. Drug spam
3. Pornography
4. Replica watches
5. Loans
6. Phishing spam
7. Pirated software
8. Fake job ads
9. Dating site spam
10. Fake diplomas