Blacklist Checker

What blacklist hits actually mean

A blacklist hit is not “game over”, but it is a signal you cannot ignore. Some lists are high-impact for deliverability (mailbox providers and spam filters actually use them), others are low-signal noise. The point of this tool is speed: detect the obvious problem early, then fix the root cause so you do not land right back on the list next week.

When you should run a blacklist check

• Deliverability drops suddenly (spam folder or hard blocks).
• You see SMTP errors mentioning “blocked”, “spam”, “reputation”, or “listed”.
• You changed ESP, warmed up a new domain, or started outreach recently.
• You are sending from shared infrastructure and want to verify you are not collateral damage.

What usually causes a listing

• High bounce rate (bad lists, old leads, scraped emails).
• Spam complaints (people hitting “Report spam”).
• Cold sending too fast (no warmup, no engagement).
• Auth misconfig (SPF/DKIM/DMARC missing or misaligned, making you look spoof-y).
• Compromised account or form abuse sending junk.

How to react smart (not emotionally)

1. Confirm what is listed: is it your sending IP, your domain, or both?
2. Stop the bleeding: pause the campaign that spiked bounces/complaints.
3. Fix authentication: if you are missing SPF/DKIM/DMARC, do that first.
4. Clean the list: remove bounces, role accounts, and risky segments.
5. Then delist: only after the cause is fixed, otherwise you bounce back fast.

Common mistakes that keep people stuck

• They request delisting immediately and keep sending the same bad traffic.
• They ignore bounces and keep hammering invalid mailboxes.
• They “fix SPF” by adding a second SPF record which breaks SPF completely.
• They have DMARC but no alignment, so spoofing protection does not actually protect.

Do this right after a blacklist check