Email Blacklist: How To Check, Avoid And Prevent It

An email blacklistThe term blacklist refers to a list of IP addresses or email domains that are,... More, also called a blocklist, is a public list of IP addresses and domains that spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More has been sent from. Mail servers look it up before accepting a message: if the sender is on it, the email can be rejected or sent to the junk folder. Finding out whether you are listed takes a few seconds.

What is an email blacklist and how does it work?

The technical name is DNSBL, and you will also see it written as blocklist or RBL: they are all the same thing. Each list is run by an independent organisation that collects signs of spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More (for example, messages that reach its spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More trap mailboxes) and publishes the IPs or domains they came from.

The mechanism is simple. When a server receives your email, it asks the list whether the IP delivering it is listed. The answer comes back in a fraction of a second and the server decides: accept, send to spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More, or reject with an error message. All of this happens before the recipient sees anything.

Lists come in two families. IP lists look at the server that sends. DomainIn technical terms, a domain name is the address used to visit a specific website.... More lists look at the names that appear in the message, such as the sender’s domainIn technical terms, a domain name is the address used to visit a specific website.... More or the domains in the links. And they do not all carry the same weight: each mailbox provider chooses which ones to consult, so being on a widely used list is felt right away, while a little-used one may have no effect at all.

How senders end up on an email blacklist

Lists do not judge intentions: they record behaviour. The cause is almost always one of these three.

Who you write to. Old, bought or scraped address lists contain abandoned mailboxes and spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More traps, placed there on purpose to spot senders who mail without permission. Hitting a few is enough.

How recipients react. If many recipients mark your messages as junk, or if a high share of emails bounces because the address does not exist, your reputation drops quickly.

Who sends in your name. A computer with malware, an unprotected formA form is a part of a web page that lets users enter information and... More on your site or a stolen password can send spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More without your knowledge. And on shared hosting one IP serves many sites: it can get listed because of someone else.

How to check an email blacklist

With MailSenpai’s free blacklist check you enter the IP your emails are sent from, or the domainIn technical terms, a domain name is the address used to visit a specific website.... More, and in a few seconds you see the result list by list. There is no sign-up.

The tool queries 15 lists: 11 for IP addresses and 4 for domains, all named on the page. If you enter a domainIn technical terms, a domain name is the address used to visit a specific website.... More, it also checks the IPs of that domain’s mail servers. If you send through an external service, the sending IP is a different one: you will find it in the headers of an email you sent, which you can read with the email header analyzer, and it is worth checking that one too.

Lists we do not query: Spamhaus, Barracuda, Mailspike, SpamRATS, Sender Score, SURBL and URIBL. Together with the result you get the link to the lookup on their official site, such as the one from Spamhaus and the one from Barracuda.

A check is a snapshot of today. So that you do not have to repeat it by hand, the same page has a free monitor: you list up to 50 entries between IPs and domains, we check them every 12 hours and email you only when something changes, that is when an entry gets onto a list or comes off one. It needs your company email and a confirmation from the link you receive. There is no account to create and you can stop it from any email.

How to read the result

For each list, the result says one of three things.

• Clean. The IP or domainIn technical terms, a domain name is the address used to visit a specific website.... More is not on that list.
• Listed. It is on the list. Next to it you get the link to the list’s official page, where you read the reason and ask for removal.
• Could not be queried. The list did not answer in time or refused the query. It means neither clean nor listed: try again in a few minutes.

Two cautions so that you do not misread it. First, a single listing does not settle everything. It matters which list it is, because every mailbox provider weighs lists differently, and whether it concerns the IP, which may be shared with others, or the domainIn technical terms, a domain name is the address used to visit a specific website.... More, which is yours alone.

Second, being clean everywhere does not mean your emails arrive. Lists are one of the signals filters look at, together with domainIn technical terms, a domain name is the address used to visit a specific website.... More authentication, content and how recipients treat your messages. To see how a filter judges one of your emails there is the free email spam test, and a separate guide explains how to read an email spam score.

How to get off an email blacklist

Order matters: first find and fix the cause, then ask for removal. Senders who do it the other way round are usually back on the list within days. The request is made on each list’s official page, the one the link next to the result takes you to. Several lists also drop the entry by themselves after a period with no new reports.

The steps one by one, including what to write in the request and when to check again, are in the guide IP or domain blacklisted? How to check and what to do.

How to avoid an email blacklist from now on

The habits that keep senders off blacklists are few, and they are always the same.

• Write only to people who asked. A contact list built on consent, ideally with a confirmation email at sign-up, is the first protection.
• Remove those who are gone. Addresses that bounce and contacts who have not opened in a long time should be cleaned out regularly.
• Make it easy to unsubscribe. People who cannot find the way out press the spamSpam is unwanted messaging: messages sent, often repeatedly, to recipients who never asked to receive... More button.
• Authenticate your domainIn technical terms, a domain name is the address used to visit a specific website.... More. 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 tell servers the email is really yours: verify them with the free email DNS checker.
• Keep a steady pace. Volumes that double overnight, especially from a new IP, are a warning sign for filters.

If your website’s emails leave from your hosting’s shared IP, its reputation depends on the other sites too. In that case it makes sense to send them through a dedicated sending service such as SMTP Senpai, which signs your messages with DKIMDKIM is an email authentication method based on a digital signature. The acronym stands for... More on your own domainIn technical terms, a domain name is the address used to visit a specific website.... More.

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