# How to check if your mail server is on an email blacklist

> Email blacklists (DNSBLs) list IP addresses that sent spam. Receivers look up the sending IP and reject or filter mail from listed ones, so a listing quietly breaks delivery for everyone on that server.

Security · HTML version: https://getreport.app/learn/email-blacklists

## What it is

An email blacklist, or DNSBL (DNS-based blocklist), is a list of IP addresses that recently sent spam, published through DNS so any mail server can ask about an address in milliseconds. When your server sends a message, the receiver checks its IP against the lists it trusts and may reject the mail, delay it or send it to spam.

getReport finds the IPs your domain controls, meaning the addresses of your own MX hosts and any single addresses in your SPF record, and asks the blacklists whether they are listed. Addresses run by hosted mail providers such as Google Workspace or Microsoft 365 are skipped: their reputation is the provider's to manage, not yours. Your setup is OK when none of your own IPs is listed. By default the check asks SpamCop, a free list run by Cisco; each deployment can add more lists.

## Email blacklists

Passing looks like: None of your mail server IPs is on the blacklists checked.

**Why it matters.** Receiving servers look up the sending IP on blacklists (DNSBLs) and reject or spam-folder mail from listed addresses. A listing usually means the server sent spam, often through a hacked account, contact form or plugin, so mail from everyone on that server suffers until it is fixed and delisted.

**How to fix it.**

1. Find and stop the cause first: a compromised mailbox, an open relay, a hacked contact form or a script sending mail. Delisting before that only gets the IP listed again.
2. Then request removal on the list's own site (each listing names the list), or wait: SpamCop listings expire by themselves once reports stop.
3. If your mail goes out through a hosting company or relay service, ask them to check the shared server; they own the IP and its reputation.

## Questions people ask

### Why did my mail server get blacklisted?

Almost always because spam left it. The usual causes are a mailbox whose password was stolen, a hacked website form or plugin that sends mail, or a script on a shared server. Some lists also catch whole address ranges of hosting companies. Find and stop the source before asking for removal, or the IP is listed again within hours.

### How do I get my IP removed from an email blacklist?

Fix the cause first, then use the removal page of the list that names you; most have a lookup and delist form. Some lists expire listings on their own: SpamCop removes an IP automatically once the spam reports stop. If the IP belongs to your host or relay service, ask them to delist it, because only the owner of the address can fix its reputation.

### Does a blacklist listing affect Gmail and Outlook?

Big providers mostly run their own reputation systems rather than public blacklists, so a listing on one list does not automatically block Gmail. It is still a strong signal that the server is sending spam, and many smaller providers, company mail servers and spam filters reject mail from listed IPs outright.

Check your own page: https://getreport.app/