Below the message on the left side there is the "report" button for that…
Users that are reported for posting SPAM are promptly flagged as spammers so that they cannot make new posts… and all posted SPAM is deleted…
so the best thing to do when you get a SPAM message is to report that message by use of the "report" button
Maybe you could add Bad Behavior http://www.bad-behavior.ioerror.us/ (to the whole site, not just the forum).
Maybe. But maybe they are automated, image recognition algorithms can defeat CAPTCHAs.
Sure about that? Just cought a spammer red-headed. Even reporting his post + the spammer himself didn’t seem to stop him from posting even more spam…
"Standard" forum users can only report a spammer and it is enough to report only one post for same user…
After that it’s needed that one of team members see the reported user to delete SPAM posts and to flag him as spammer so that it cannot post anymore…
I have just done that for this user you reported…
Thanks for reporting him…
Why am I getting SPAM messages in my Inbox?
problem is that some "smart" spammers register to this forum and send private messages (smarter ones avoiding to send it to the dev team)…
as this messages are private we (administrators and the dev team) cannot see them to check if it’s a SPAM… until someone reports that message…
When a private message is reported we are notified and can react accordingly…
Edit:
-private messages are sent to the registered e-mail, probably is that the reason why you got the SPAM message…
I got one some hours ago 
I guess there’s no option in IPB to allow privates messages after 1 post?
This time I got it too, and as soon as I saw it… deleted the user… but he managed to send some PMs in the meantime, as it seems…
I don’t know for this option, but it would be of no use… as a spammer can post one replay to any thread and after that send all this messages…
Yes true, well at least it would help a little bit in the usual times when admins/mods are online.
Why not using whitelist instead of blacklist?
I mean, instead of blocking spammers, the first time one send a PM to another, both receive an email.
The sender should click a link to confirm he/she is a regular user and a real person
The receiver should read the message to accept it
Once the message has been accepted as regular and the sender has clicked the "i am human" link, sender username/id is stored in a whitelist
Whitelisted users could send PM messages to others (obviously, respecting user’s personal block lists)
This way admins should not worry about blocking users, once it would be "automatically" done…
I have just received spam from sylvia4you
regards!
Yes, today we have an attack from a user registering with different accounts… I already blocked 3 - sylvia, sylvia4u, sylvia4you…
Your idea is still not good… as all those spammers are real humans… this is not automatic spam posting…
so even if your idea would be implemented… this spammer could click "i am a human"… send one normal message to get approved… and then send spam…
Thanks for blocking them!
Yes, you are right, didn’t know they are real people.
Regards!
I have just received spam from sylvia4you
same here
sylvia4u sent me a message just yesterday.
Why not only allow a user to privately message other users after like 5 or 10 posts (not just 1 post)? Forum posts can be seen by all forum members, and can be detected faster if it is a spam user.
On the other hand, a spammer can just reply "ok" or "thanks" to 10 forum posts, then proceed on sending private spams.
…
How about implementing a “Report as Spammer” button beside the “Report Member” link button in the user’s profile?
Report Member is an overall complain about a particular member. A victim writes a complain, forum admins (who are available) read the complain then apply appropriate actions.
Report As Spammer button will act like a "vote" button, so spammers can be quickly identified. After a certain number of votes, say three or five or ten, the spammer will no longer be allowed to post something in forums and even send personal messages until an admin clears his "spammer" status. If this can be programmed, admins and developers can focus more on improving the framework or answer forum questions.
If there is a Report As Spammer button on profiles of new users, even regular users can do something to prevent a spammer (or suspected spammer) from spreading spam messages. As a standard forum member, we also have responsibilities to keep this forum "healthy and safe".
Just my two cents.
You need to understand that the forum software is not our… but IPB - http://www.invisionp…products/board/
We can add/change a bit here and there to add more checking… but do magic 
we are currently trying to add some checks so that only users with some posts can send messages… but again this case with "sylvia" is where not PM but comments on user profiles where posted…
and you all need to understand that as we add more anti-spam checking… more new users are prevented of doing this actions… and are complaining when they want to post proper content…
so it’s very difficult to find a good solution so that all spammers are prevented and at the same time that all users are happy…
but we are working constantly on this
So I guess we should all be more vigilant then
Yes this is a SPAM… I just deleted it…
when we flag this user that has posted that comment as a SPAMMER, those comments are not removed automatically… you need to delete it yourself… in your case i deleted it…
Qiang added today a new anti-spam measure…
now new users cannot post comments on user profiles if they don’t have at least 3 forum posts… we hope that this will prevent problems like this “sylvia” user did in previous days…
thanks to all that reported SPAM comments, continue to do so if you find any spamm activities… this is the best way to let us know that something is wrong…
It’s quite clear now that antispam measures used here are not enough (I’ve just seen 2 pages of new spam posts today).
Additionally once in a while we can read the post with complaint about the forum hamstring some fair new user.
What can we do to change it? Maybe some graphic captcha with every post where you have to mouse drag specific object and drop it in the selected field? This takes few seconds and shouldn’t be so tedious as typical captcha is.
I’m not sure how effective this is though.
PS. Quick google search got me this http://portal.areyouahuman.com/installation/ipb