Spammers have come up with new ways to evade spam filters. Content of emails have been changed from day to day so that the emails are not detected and on top of that, images have been used widely to prevent the filter to 'read' the email. Furthermore, IP blocking is becoming less effective as these emails are sent from different locations.

Our spam filter machine is updated with the latest pattern of spam mails but as mentioned earlier, day to day, the patterns are changing and it has become a continuous task. It takes bit of time for the filter to start learning the new pattern of spam mails. This is actually a common problem, faced by everyone who own a domain name on the Internet as users are more exposed to these spam emails.

The site below delivers information on spam outbreak and it's effect:

http://www.networkworld.com/news/2006/111306-spam-increase.html?page=1 

We recommend you to use CAPTCHA technology for your website forms to encrypt the information which will lead to less spam mails. Kindly visit the link below for more information:

http://en.wikipedia.org/wiki/CAPTCHA

Please beware that open source scripts such as phpbb, wordpress, joomla and etc. are more exposed in some way by spammers and spam-bots. However, the recent versions already have built-in protections but to have this, it is advisable to keep your scripts up to date.