IP or domain blacklisted? How to check and what to do

Are your emails bouncing with an error that mentions a list, or have they been landing in spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More for a few days for no clear reason? The IP you send from, or your domainIn technical terms, a domain name is the address used to visit a specific website.... More, may be on a blacklist. Here is how to check in a minute and what to do, in the right order.

What an email blacklist is

A blacklist (or blocklist, technically a DNSBL) is a public list of IP addresses or domains that spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More has been sent from. Each one is run by an independent organisation. Mail servers query it in real time whenever they receive an email: if the sender is on the list, the message can be rejected or sent to spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More.

Not all lists are the same. Some list IPs (the server that sends), others list domains (the ones in the sender address or in the links). Some are used by a great many mailbox providers, others by very few: being on a little-used list often changes nothing, being on a major one is felt right away. For the basics, see the guide on what an email blacklist is and how to check it.

How to tell if you are listed

There are three typical signs:

• a bounce message that names the list, for example 554 5.7.1 followed by the name of the service that blocked you;
• bounces that suddenly rise towards a single mailbox provider;
• opens that drop overnight although you changed nothing.

One check settles it: enter the IP or the domainIn technical terms, a domain name is the address used to visit a specific website.... More in the free blacklist check and see, list by list, where it shows up. For a domainIn technical terms, a domain name is the address used to visit a specific website.... More, the IPs of its mail servers are checked too. If you do not know the IP you send from, you will find it in the headers of an email you sent (the Received line), which you can read with the email header analyzer, or you can ask whoever runs your sending service.

Why senders get blacklisted

• SpamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More traps. Mailboxes created on purpose, or abandoned for years, that no person uses. Writing to them is the strongest sign of an old, bought or scraped list.
• SpamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More complaints. Too many recipients press the spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More button.
• A compromised site or computer sending without your knowledge: an unprotected contact formA form is a part of a web page that lets users enter information and... More, a stolen password, an outdated pluginThe term plugin (also called an extension or add-on) comes from computing. It refers to... More.
• A shared IP. On shared hosting one IP sends for hundreds of sites: one bad neighbour is enough to get everyone listed.
• Sudden volume from a new IP that was never warmed up gradually.

What to do if you are listed, in this order

1. Find the cause before asking for removal. If the cause stays, you are back on the list within days and the second request is treated worse than the first.
2. Fix it. Remove addresses that bounce and those that have not opened in a long time, close the compromised formA form is a part of a web page that lets users enter information and... More or account, change passwords and verify SPF, DKIMDKIM is an email authentication method based on a digital signature. The acronym stands for... More and DMARCDMARC is the system created to ensure email compliance and integrity. Short for Domain-Based Message... More with the free email DNS checker.
3. Ask for removal on the list’s official page. Every list has its own: in the check result you find the link next to each name. Some drop the entry by themselves after a few days with no new spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More, others ask you to fill in a formA form is a part of a web page that lets users enter information and... More. Ordinary removal is free: if a list offers a paid fast lane, waiting for the automatic expiry is usually enough.
4. Keep it short and factual. Say what happened and what you fixed. The person reading decides on that.
5. Check again after 24 to 48 hours and keep an eye on it over the following days.

How to stay off the lists

Send only to people who asked for it, remove bounces right away, keep a steady pace and authenticate your domainIn technical terms, a domain name is the address used to visit a specific website.... More. And do not wait for a customer to tell you that emails are not arriving: the free monitor, on the same page as the blacklist check, rechecks up to 50 IPs and domains every 12 hours and emails you only when something changes.

If the problem is your hosting’s shared IP, the shortest way out is to send your site’s emails through a sending service with well-kept IPs, such as SMTP Senpai. And if you want to know how a filter judges one of your messages, there is the free email spam test.

Frequently asked questions