Blacklist, No-List, Delist, Whitelist

Everyday we get requests to “Whitelist” an IP.  To quote the great Inigo Montoya, “I do not think it means what you think it means.”  When talking about Blacklisting, Delisting, Whitelisting and not being on a list at all, you need to need to understand exactly what it is you are requesting. So, here are a few definitions to help you talk about what is actually going on.


When an IP or domain is blacklisted, traffic from or to that location is cutoff.  Typically, blacklisting is due to some bad action on the part of the IP address or domain owner, like sending spam, being infected with malware or viruses or facilitating spam through a bad mail configuration.

Short-term blacklisting is a wake up call to fix problems and harden your email or web server security.  Long-term blacklisting will cripple the business run from that IP address or web server.  We provide much more information on blacklisting throughout our blacklist-specific blog articles.

For more information on the blacklists we curate, check out our blacklist information page.


No-list simply means that you are not listed on a blacklist, whitelist or greylist.  This is good.  It means no one out there is concerned about your IP address or domain.  Basically, no-list is business as usual.


When you are on a blacklist, you can ask to be removed from the blacklist.  This is called delisting.  A delisting request should be made to the blacklist agency that has you listed.  MxToolbox aggregates and curates our list of blacklists and provides delisting support to our paid customers.  We don’t run the lists and we cannot help you if you haven’t already performed the necessary minimum steps for delisting:

  • Remedy the problem with your servers.  Stop the spam, fix the configuration, purge the malware or viruses, rebuild if you have to.
  • Contact the blacklist and request delisting.  Some blacklist will not have a contact for and will automatically delist you after a period of time wherein no new spam issues arise.
  • Wait.  Delisting takes time.  We understand the pain of being blacklisted and how that can affect your business and revenue, but delisting does not happen overnight.  Blacklists need to wait to make sure they are delisting legitimate businesses while still catching spammers.  If they delist you too early, they lower their reputation as a valuable mechanism to combat spam.


Many blacklist operators have a second, less severe category for activity that isn’t considered overtly malicious, but is considered to be problematic.  These operators may choose to classify an IP address or domain name in this state as greylisted.  Greylisted simply means that the servers have done something bad, but not enough to have traffic completely banned.  Greylisted IP addresses and domain names could eventually be promoted to full blacklisting or unlisted entirely.

At MxToolbox, we are primarily concerned with Blacklisting.  Greylists are less common and the coding for greylists is inconsistent across blacklist providers.  If this is something you would like us to add, send email to our feedback address.


Many of our customers ask us to whitelist their IP address or domain names.  First, let me be 100%, we will never whitelist you.  I will explain.

Whitelisting an IP address or domain name means that we will always accept traffic from that server.  Whitelisting implies that the server is 100% clean, trusted and traffic from there is always valid.  Most companies will only whitelist highly trusted, internal, highly secured servers.  While we love our customers, we don’t know you that well!

If you are blacklisted, asking a company to whitelist you is like toilet papering a house and then asking for keys to the front door.  Fix your mistakes, build up your reputation, make amends, then maybe you will be trusted at some point down the road.  Not today.  What you really want when you are blacklisted is delisting.  

Note:  MxToolbox maintains a list of servers that we use to monitor our customers’ systems and setups.  These should be whitelisted so that we can accurately monitor your servers.

For more information on our monitoring solutions, check out our feature comparison page.