In the last few months, there has been a lot of several user of Indonesian Linux Forum who complaint about their IP was being blocked due to being blacklisted by SpamHaus. Those who have registered will not be able to post a message or reply a thread while the new user will not be able to register to the board.
The message that they got looks like this:
Your IP aa.bb.cc.dd has been blocked because it is blacklisted. For details please see http://www.spamhaus.org/query/bl?ip=aa.bb.cc.dd
What is SpamHaus anyway? It's a volunteer effort founded by Steve Linford in 1998 to track e-mail spammers and spam-related activity (taken from Wikipedia). On their operation, they are using four services, which are DNS Blocklists (DNSBLs), Spamhaus Block List (SBL), Exploits Block List (XBL), and the Policy Block List (PBL).
If your IP is blocked by the board, it's not because we hate you guys, but it's because the phpBB engine used SpamHaus to verify every IP address that were used to post or register to the board before it can be process the requests. If your IP are listed on the blacklist, the board will reject your request and asked you to solve the problem before you retry.
My suggestion is to go to link displayed by the board (which will redirect you to SpamHaus website) and see in which category are your IP in (SBL, PBL, or XBL). You can ask them to remove your IP from their blacklist (take a look on the bottom of the page after you click one of the link given by the SpamHaus), but it's also good idea to scan your network for spyware or any other malicious program which uses your network to send spam messages to other people. If they caught your IP again in the future, it will be harder to delist your IP from their list.
Please note that if you use shared IPs, then there might be a big chance that the root cause was caused by other users who used the same ISP with you and their action caused the IP is blocked by the SpamHaus. So you should also report this to your ISP and asked them to check it (and hoping they would do that ).
I hope this post will help those who had problems with Indonesian Linux Forum and SpamHaus.