Blacklist checker — check an IP on RBLs
Enter your mail server's IP. We query 8 DNSBLs through our own resolver (Spamhaus blocks public resolvers) and check PTR.
Which lists matter
Spamhaus ZEN (SBL + XBL + PBL) — used by most MTAs worldwide; an SBL/XBL listing means real rejections. PBL lists dynamic/consumer ranges — if your IP is in PBL, send through a relay or move to a server IP. SpamCop — adds quickly after user reports, expires in 24–48 h. Barracuda — used by Barracuda gateways in enterprises. SORBS, PSBL, UCEPROTECT — smaller impact; UCEPROTECT level 2/3 lists whole provider subnets and is not worth paying for.
How to get delisted
Remove the cause first: compromised account, open relay, form without captcha, infected WordPress. Then delist: Spamhaus — free form on spamhaus.org, SpamCop — expires on its own, Barracuda — form with justification, SORBS — ticket. After delisting ramp volume gradually; Gmail and Microsoft reputation recovers slower than the listing.
FAQ
My IP is clean but mail still bounces — why?
Gmail and Microsoft keep internal IP and domain reputations invisible in DNSBLs. Check Google Postmaster Tools and Microsoft SNDS, and above all send a test email — you will see PTR, TLS, authentication and content.
Do you check the domain too?
Yes, in the DNS audit: Spamhaus DBL, SURBL and URIBL — lists of domains used in spam and phishing.