IP block list and blacklist lookup is a virtual database that contains information about IP addresses and domains associated with spam, unwanted activity and other negative online behavior. When your server or website’s IP address gets on one of these lists, ISPs and web servers will flag it and block any subsequent traffic from it. Using a blacklist checker like MxToolbox, MultiRBL or What Is My IP Address will help you determine if your server has been flagged and if you need to take steps to resolve it.

Most people get put on a block list because of illicit behavior, such as spamming or running a bot. But sometimes a server or email account gets flagged when it is on the same network as infected PCs or compromised websites. Then, a high volume of suspicious activity such as multiple failed login attempts or excessive form submissions can lead to being blocked.

IP Block List and Blacklist Lookup: Protect Your Network from Threats

The good news is, getting your IP removed from a block list doesn’t have to be difficult or time-consuming. It is simply a matter of fixing the issues that got you there in the first place.

There are two main types of block lists, email and DNS blocklists. An email blocklist works with emails and ensures that spam and other malicious or potentially harmful messages don’t reach the intended recipient, while a DNS-based blocklist blocks all requests to specific domain names, which can include sites used for spamming, malware distribution, or identity theft. The best way to avoid being blocked is to make sure you use an email host that can keep its servers clean of malware and maintain proper security practices.