How to check if your domain is on an email blacklist (and what to do if it is)

If your emails are suddenly going to spam or not arriving at all, a blacklist is one of the first things to rule out. Blacklists are databases of IP addresses and domains that have been flagged for sending spam. Major email providers check these lists before deciding where to deliver your mail.

Here is how to check if you are listed and what to do about it.

What gets blacklisted

Both your sending IP address and your domain can be blacklisted independently. An IP blacklisting affects every domain that sends through that IP. A domain blacklisting follows your domain regardless of what IP you send from.

Common reasons for being blacklisted:

• Sending to addresses that have not opted in
• High spam complaint rates (anything above 0.1% with Gmail will hurt you)
• Sending to spam trap addresses
• A sudden spike in sending volume from a new domain
• Your shared hosting IP was blacklisted by a different tenant (common on shared servers)

How to check

The fastest way is to use a blacklist lookup tool. InboxGreen has a free blacklist checker that checks your domain against the major lists used by Gmail, Outlook, and other providers.

You can also check manually:

Spamhaus (spamhaus.org/lookup) is the most important one. Gmail and Microsoft weight Spamhaus heavily. If you are listed here, expect significant deliverability damage.

Barracuda (barracudacentral.org/lookups) matters mainly for corporate email delivered through Barracuda gateways, which is common in enterprise environments.

MXToolbox (mxtoolbox.com/blacklists) checks against around 100 blacklists at once. Free, no account needed, good for a broad sweep.

If you are on shared hosting (Namecheap, Bluehost, SiteGround), always check the IP address of your mail server too, not just your domain name.

How to get delisted

Each blacklist has its own removal process.

Spamhaus: Go to spamhaus.org/lookup, enter your IP or domain, and follow the removal link. For legitimate senders who ended up listed by mistake, removal is usually granted within 24-48 hours if you can explain what happened.

Barracuda: Fill out the removal request at barracudacentral.org/lookups. Approved within a few hours for clean IPs.

SORBS: Slower process, often requires waiting out the listing period and demonstrating clean sending behavior over time.

Before requesting removal from any list, fix the underlying problem first. If you request removal without stopping whatever caused the listing, you will be relisted quickly and future removal requests may be ignored or delayed.

Staying off blacklists

The best approach is prevention:

• Keep spam complaint rates below 0.08% (Google's threshold before they start filtering)
• Never send to purchased or scraped lists
• Set up SPF, DKIM, and DMARC — authenticated domains are less likely to be listed
• Warm up new domains gradually, starting at 20-50 emails per day and scaling over 4-6 weeks
• Remove unengaged contacts regularly before complaint rates climb

Checking your deliverability setup before it becomes a problem is much easier than recovering from a blacklisting. InboxGreen's full domain check covers SPF, DKIM, DMARC, and blacklist status in one scan, no login required.