Hi Fetze and willkommen.
Spam is a problem for any board and we've certainly had bad times in the past. However, it comes and goes. We have it under control at the moment, but it's a cat and mouse game.
Thanks for the list of anti-spam tips. We have used some of them at one time or another with varying success.
One of my first mods was to insert custom fields in the posting page. Some spambots simply send a HTTP POST with the message data rather than actually filling in the post form. So I included a time-stamped hash value on the post page that allowed me to filter in a number of ways:
* Any POST without the custom field obviously hadn't come from the post page and could be rejected.
* Any message that was submitted within 5 seconds of the timestamp generation was probably automated and was rejected.
* Any message that was submitted over 1 hour from the timestamp generation point was old or a resubmitted value and was rejected.
That worked for a while, but I suspect that some spamming outfits actually use real humans to do the dirty work. There are plenty of places in the world where you can get someone to sit at a computer all day and do donkey work for pennies and the best way to defeat anti-bot measures is to not be a bot. I didn't bother with this mod back after a few updates.
We do limit hyperlinks, but that is a pain for regular users. I should modify that to allow members with a certain number of posts to be exempt, but that brings the problem of people posting junk to reach the magic post count milestone.
It's nice to see Askimet in your list, I've used that on WordPress and it's very good. I looked at it in phpBB a while back, but there was no easy way to integrate it. Seems like there might be a better way now.
It's an unfortunate fact that if something works well to combat spam, it becomes popular and that attracts attention from the spammers to get around it. Our captcha is fairly rare and as such does a good job, I'm sure as it gains popularity it will be bypassed. reCaptcha is now completely useless as an anti-spam measure for this reason.
Anyway, I've rambled on long enough here, the honeypot looks cool and I'll be sure to take a look at that.