Check if an IP address or mail server is listed across major DNS-based real-time blacklists (DNSBL / RBL). Essential for email deliverability and reputation hygiene.
If your emails are landing in spam or bouncing, one likely cause is that your sending IP or mail server has been listed on a DNS-based blacklist. These real-time blocklists (DNSBLs or RBLs) — run by organisations such as Spamhaus, Barracuda, SpamCop and SURBL — catalogue addresses associated with spam or abuse, and many mail providers consult them before accepting a message. This tool checks an IP or mail server against the major lists at once so you can see where it stands.
A listing does not always mean you did something wrong: shared hosting, a compromised device on your network, or simply inheriting a previously abused address can all put you on a list. Knowing which list flagged you is the first step, because each publishes its own delisting process and the reason for the entry, which you address before requesting removal.
Reputation is central to email deliverability, so this check is worth running whenever mail stops arriving reliably, after setting up a new sending server, and periodically as maintenance. Combine it with proper SPF, DKIM and DMARC records — which the email header analyzer here can help you verify — for the best chance of reaching the inbox.
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