I guess all have issues with spam. I have had some success with using DNS blacklist filters. It takes out about 80% of the spam (only judging by the massive domino logging it produces, I have not counted them) but some still slips by.

I am using the following blacklists at the moment:

cbl.abuseat.org
taiwan.blackholes.us
opm.blitzed.org
dnsbl.njabl.org
dynablock.njabl.org

If you have any better ones feel free to share. My settings are listed in the picture below. 

Also if you have any experience with other filters I would like to know about it.

Tomas,

I use  bl.spamcop.net for DNS Blacklist Sites, seems to work pretty good. Not sure a % in terms of how much gets through still but may be beneficial to you.

Hope this helps!

Thanks for the tip Bryan. I will add it and see if it helps.
Do you have a feeling if they are agressive in their filtering or more moderate?

This was taken from their website .

"The SCBL is aggressive and often errs on the side of blocking mail"

http://spamcop.net/anonsignup.shtml

I am trying out SpamSentinels free Back Scatter protection now. I will see how it works out.

I was getting really annoyed with all the spam I get lately. Unfortunately my e-mail address is kind of public since my domains are registered to me so all the spammers can pick it up.

So I did some more research and stumbled upon the kSpam project over at www.openntf.org.

The first release was 5 years ago so I am amazed I have not heard about it before. It is a completely free spam solution and it learns from your spam and your good e-mails using a Bayesian algorithm to calculate probabilities that e-mail is spam.

The documentation is quite old and says nothing of Domino 8 although on the openntf pages it states to support Domino 8 (and it seems to do).

I went ahead and tested it last night and although I have not enough spam to get the algorithm working at its best it has already found 9 spam mails that never reached my inbox.

If you want to use the Bayesian filter (there is a rule based filter also but I do not use that) you must add the line bload to your ServerTasks line in notes.ini. That one was a bit tricky to figure from the doc's.

Judging from 5 hours of usage I can recommend this one.