Getting Delisted From a Blocklist

If legitimate mail is being rejected outright rather than filed into junk folders, your domain or the address you send from may be listed on a blocklist, and this article shows you how to confirm that and how to get removed.

Blocklists, sometimes called blacklists or DNSBLs, are public lists of domains and network addresses associated with spam. Receiving mail servers query them during delivery and refuse anything that appears. A listing is not permanent and is not a judgement you have to live with, but it does have to be dealt with at the list operator's end, not at ours.

First, Confirm It Is Actually a Listing

A blocklisting has a specific signature. Before you spend an afternoon filing delisting requests, check that this is what you are dealing with.

Symptom	Likely cause
Mail is rejected with a bounce mentioning a blocklist or a policy refusal	A listing. Continue with this article.
Mail is accepted but lands in the junk folder	Not a listing. Read Why Are My Emails Going to Spam?.
Mail is deferred with a temporary code and eventually arrives	Not a listing. Read Understanding Bounce Messages.
Only one recipient's organisation rejects you	Usually their own local block rule, not a public list.

Read the actual bounce text. A genuine blocklist rejection almost always names the list, and often includes a URL to that list's own lookup page. That URL is the fastest route to the right delisting form, and it saves you guessing which list is involved.

Ask Kora to Check

The quickest check is to ask Kora, the assistant in KPanel. Open Kora and ask it to check whether your domain is on any mail blocklists. It queries the major lists for your domain and its mail server address in one pass and reports back which, if any, have you listed.

Kora can also run a wider security check that queries domain-reputation lists used to score links inside messages, which is worth doing if your mail is being rejected because of what is in it rather than where it came from.

Check It Yourself

Two free tools cover most of what matters:

MXToolbox blacklist check at mxtoolbox.com/blacklists.aspx. Enter your domain or your sending address. It queries dozens of lists at once and each result links to that list's own removal process.
The list's own lookup page. Every major operator publishes one. If a bounce names a list, go straight there: the operator's own page tells you the reason for the listing, which is information the aggregators usually do not have.

Deliverability tab for a mailbox in KPanel

Domain Listings Versus Network Listings

This distinction decides who does the work, so establish it before doing anything else.

Your domain is listed. The list names your domain, or the domain of a link inside your messages. This is yours to fix: something sent from or referencing your domain triggered it. Common causes are a compromised mailbox, a website that got hacked and was serving spam links, a form on your site being abused to relay mail, or a bulk send to a purchased list.

The sending network address is listed. The list names an IP address rather than a domain. Kapsule operates the sending infrastructure, so that is ours to investigate. Open a support ticket with the exact bounce message including the full error text, the recipient address, and the time it happened. Do not file a delisting request yourself for infrastructure you do not control.

If you are not sure which you have, the bounce usually makes it obvious: a domain listing names a domain, and a network listing names four numbers separated by dots.

Fix the Cause Before Requesting Removal

Requesting delisting without fixing what caused the listing wastes the one thing you cannot get back: most list operators are markedly less willing to remove a domain a second time, and some impose a waiting period after a repeat listing. Find and close the cause first, then request removal once.

Work through these in order:

Change the password on every mailbox at the domain. A compromised mailbox is the most common cause of a sudden listing. Use the Password tab on each mailbox in KPanel. See Account Security.
Check your sending volume. If a mailbox has been sending far more than its owner realises, something is using its credentials. The caps described in Email Sending Limits contain the damage but do not tell you the cause.
Check your website. A hacked site serving spam pages gets the domain listed even if no mail was ever sent from it. Run the malware scan on the site's Security page.
Check your forms. A contact or quote form that emails arbitrary addresses supplied by the visitor is a relay, and it will be found and used.
Verify your authentication. Open the Deliverability tab on a mailbox at the domain and get SPF, DKIM and DMARC to Configured. A domain that cannot prove who it is gets listed far more readily. See SPF, DKIM and DMARC Explained.
Clean your recipient lists. Remove every address that has permanently bounced. Repeated delivery to dead addresses is itself a listing trigger.

Requesting Delisting

Once the cause is closed:

Go to the list operator's removal page, which the bounce or the MXToolbox result links to.
Enter the domain or address being delisted.
If the form asks what happened, answer honestly and specifically. "A mailbox password was compromised on the fourteenth, we rotated every password and enabled two-factor authentication" gets processed. "We do not send spam" does not.
Submit once and wait.

Turnaround varies by operator from minutes to several days. Do not submit repeatedly: duplicate requests are usually queued behind each other and slow you down.

Some lists remove entries automatically after a quiet period and offer a one-time self-service removal you can only use once. If the operator offers self-service removal, save it for after you have genuinely fixed the cause, not as your first attempt.

Provider-Specific Blocks

Being refused by one large provider is not the same as being on a public list. Google and Microsoft both maintain their own internal reputation systems and their own removal processes:

Google and Gmail. Verify your domain in Google Postmaster Tools at postmaster.google.com and read the spam rate and domain reputation figures. They are the closest thing to a scoreboard you get.
Microsoft, Outlook and Hotmail. Use Microsoft SNDS for sending reputation, and their postmaster support form for a delisting request.

Both publish their own bulk sender requirements. If your mail fails those requirements, no amount of delisting requests will help until it passes them.

After Delisting

Reputation recovers, but not instantly. Expect a period where mail gets through but is filtered more aggressively than it used to be. During that period:

Keep volumes modest.
Send to people who reply. Engagement is the strongest positive signal available.
Do not run a campaign to prove things are fixed.
Re-check the lists a week later to confirm the removal stuck.