DNSBL / RBL (Blocklist)
A DNSBL (DNS-based Blocklist), also called an RBL, is a published list of IP addresses or domains flagged for sending spam or malicious traffic.
Mail servers and security systems query DNSBLs to decide whether to accept or reject traffic from a given IP. If your sending IP lands on a major blocklist, your emails get rejected or sent to spam, often without any bounce you would notice.
Blocklist monitoring checks your IPs and domains against well-known lists and alerts you the moment you are listed, so you can request delisting before deliverability collapses.
Know the moment your IP hits a blocklist
Uptimeify checks your sending IPs and domains against the major DNSBLs continuously and reports every listing while delisting is still quick.
Free for 14 days
Just need a quick look? Check blocklist status for free
Google shows sources you mark as preferred more often in its answers.
Start monitoring in minutes
EU-hosted uptime monitoring with multi-location confirmation that kills false alarms, white-label for agencies.