Mail & blacklist
MX, SPF, DMARC and DKIM for a domain, plus a check of its mail servers against public DNS blocklists.
Frequently asked questions
My IP is listed. What now?
Find and stop the cause first — a compromised account, an open relay or a bulk send. Then follow the delisting process on that list's website. Many lists remove an IP automatically after a quiet period.
Why are some lists shown as 'could not check'?
Some blocklists, such as Spamhaus, refuse queries that come through large public resolvers. The result is unknown, not clean.
What DMARC policy should I use?
Start with p=none and a rua address to collect reports. Once legitimate mail passes SPF or DKIM alignment, move to p=quarantine and then p=reject.
Tools
DNS propagation checkerQuery resolvers around the world and the zone's authoritative nameservers in one go, and see on the map where your change has arrived.PingRound-trip time and packet loss from our server. Use TCP mode when a host drops ICMP.TracerouteThe path packets take from our server to the target, hop by hop, with the network (ASN) each router belongs to.SSL / TLS checkCertificate validity, chain, hostname match and which TLS versions the server accepts.Port checkIs a TCP port reachable from the internet? Test a server, or your own connection to confirm port forwarding.HTTP headersFollow the redirect chain, see response headers and timing, and grade the security headers.WHOIS lookupRegistration details for a domain or the owner of an IP range, straight from the registry's WHOIS servers.Subnet calculatorEnter an address with a prefix or a mask, for example 192.168.10.37/26 or 10.0.0.1 255.255.240.0.What is my IP?This is the address websites see when you connect to them.