Apologies for the delay in providing a response to this issue.
Firstly, I confirm that anti-spam continues to be very much a core part of our business. The current version of Exclaimer, Version 4.24, has several improvements and we have several new developments on the horizon that will ensure we remain highly effective. Unfortunately some of these developments have taken a little longer than we intended.
However, to shed some light on where we are going, our next main release will be Exclaimer 4.3. We are aiming for a release before the end of December with the key new features being Zero-Hour Anti-Virus protection and Auto-Whitelisting.
Zero-Hour Anti-Virus is described in detail here: http://www.commtouch.com/site/OEM/zero_hour.asp
Auto-Whitelisting works on the principle of automatically whitelisting the recipient of any outbound message from your organisation. This means that most of your genuine customers will very quickly become whitelisted. In conjunction with some of our other enhancements, this will mean that you can be much more aggressive in the way you deal with BULK messages.
We are about to release a document that describes how to quarantine [BULK] tagged messages to a central Public Folder. This avoids delivering these messages to the end users and allows an administrator to periodically check for false positives. When coupled with the auto-whitelist feature you will find very very few false positives occurring.
Unfortunately spam, like viruses, is constantly evolving. As new anti-spam techniques render certain types of spam ineffective, so the spammers design new ways around these techniques. Our detection centre takes care of this to a large extent, but every now and then it becomes necessary to actually change the Exclaimer code. When this happens there is always a small period between the change in spammer tactics and the creation, testing and release of new code, at which time received spam levels will increase slightly. Our new version should make this effect far less noticeable.