How an email address gets checked
Blacklists do not list single mailboxes like [email protected]. They list domains and IP addresses. So when you enter an email address, we use the part after the @ sign and work from there. Nothing is sent to the address, and the person who owns it is never contacted.
The check runs in three parts. First, the domain itself is tested on domain blacklists such as Spamhaus DBL, SURBL and URIBL. These lists catch domains that show up in spam, either as the sender or in links. Second, we look up the domain's MX records and the IPs behind them and test those IPs on IP blacklists such as Spamhaus ZEN, Barracuda BRBL and SpamCop. Third, we read the domain's SPF, DKIM and DMARC records and flag anything that would make mail fail authentication.
Why your sending IP may differ from your MX servers
MX records show where a domain receives mail, which is often not where it sends from. A company may receive mail on Google Workspace or Microsoft 365 but send newsletters through a marketing platform and invoices through its own app server. Each of those sources has its own IP.
To find your real sending IPs, open a message you sent and view the original headers. The first Received line added by the receiving server shows the IP that delivered it. Check that IP with the IP blacklist checker. Your SPF record also lists the services allowed to send for you, which is a good map of where to look.
Reading your results
| Result | What it means | What to do |
|---|---|---|
| Domain listed on Spamhaus DBL | Your domain appeared in spam, often in links. Many filters reject mail that contains it. | Find what triggered it, fix it, then request removal through Spamhaus. |
| Sending IP listed on a major list | Mail from that server may be blocked or filtered. | Fix the cause on the server, then delist. See the blacklist directory. |
| Listed on a minor list only | Limited effect on most receivers. | Note it, fix the cause, request removal when convenient. |
| SPF, DKIM or DMARC missing | Mail may fail authentication at Gmail, Yahoo and Outlook.com. | Publish the missing record and verify it. |
| Everything clean | No listing and authentication records in place. | Set up monitoring so you hear about the next change first. |
Common reasons an email domain gets blacklisted
Cold email teams run into the last two often. Our guide to cold email domain rotation covers how to spread volume and protect your main domain.
- Sending to old or purchased lists that contain spam trap addresses.
- A hacked mailbox or website form used to send spam in your name.
- Links in your emails pointing to a domain that is already listed, such as a shared link shortener.
- High complaint rates when people mark your mail as spam.
- A new domain sending large volume on day one without warm up.
- Cold outreach at scale from a primary domain instead of separate sending domains.
How to check an email domain manually
Doing this for one domain takes a few minutes. Doing it every hour for every domain you send from is where a tool earns its place.
- 1 Take the domain after the @, for example example.com.
-
2
Check it on a domain list with
dig +short example.com.dbl.spamhaus.org A. An answer in 127.0.1.x means listed. -
3
Find the mail servers with
dig +short example.com MX, then resolve each hostname to its IP. -
4
Reverse each IP and query IP lists, for example
dig +short 10.113.0.203.zen.spamhaus.org A. -
5
Read the SPF record with
dig +short example.com TXTand the DMARC record at_dmarc.example.com.
Blacklists are only part of deliverability
A clean result does not guarantee the inbox. Gmail and Yahoo rely heavily on their own reputation data, and since February 2024 they require bulk senders (over 5,000 messages a day to their users) to have SPF, DKIM and DMARC, one-click unsubscribe for marketing mail, and a spam rate under 0.3%. Microsoft added similar rules for high volume senders to Outlook.com in May 2025. If mail lands in spam with no listing, run the email deliverability test to check DNS setup across the board.
Monitor every domain you send from
BlacklistMonitoring watches your domains and sending IPs on 100+ lists, plus SPF, DKIM, DMARC, MX and PTR records, and sends an alert by email, Slack, Teams or webhook as soon as something changes. Every alert explains the finding in a plain sentence and gives the fix. Business and higher plans add Google Postmaster Tools, Microsoft SNDS and Yahoo signals and spam rate alerts at 0.1% and 0.3%. Read more about blacklist monitoring or see the plans, starting at $24 per month billed yearly.
Frequently asked questions
Can a single email address be blacklisted?
Usually no. Public blacklists list domains and IP addresses, not individual mailboxes. Some private filters block single senders, but those lists are not public, so the useful check is the domain and the IPs that send its mail.
How do I know if my email is blacklisted?
Enter your address in the check above. Signs in daily use include bounces that mention a list name like Spamhaus or Barracuda, sudden drops in open rates, or replies saying your mail went to spam.
Does checking an email address send it a message?
No. The check uses DNS lookups only. Nothing is sent to the address or the domain, and the owner is not notified.
Why is my email going to spam if I am not blacklisted?
Mailbox providers also weigh authentication, complaint rates, engagement and their own reputation scores for your domain and IP. Missing DMARC, a high spam rate, or a sudden jump in volume can all send mail to spam without any public listing.
What does a 550 error with a blacklist name mean?
It means the receiving server rejected your message because your sending IP or domain is on that list. The bounce text usually names the list and links to a lookup page, which is the place to start the removal.