Blacklist Checker

Instantly check an IP or domain against major email blacklists including Spamhaus, SURBL, SORBS, and more.


Use Blacklist Checker


CIDR to IP Range

Enter a CIDR notation to instantly convert it to an IP range.


Use CIDR to IP Range

SPF Analyzer

SPF is a method to prevent email sender address forgery. Enter your domain to analyze its SPF record.


Use SPF Analyzer


IP Range to CIDR

Enter a IP range to instantly convert it to a CIDR notation.


Use IP Range to CIDR

DMARC Wizard

Enter your domain to analyze your DMARC record or create a DMARC policy for your domain.


Use DMARC Wizard


DNS Lookup

Perform a DNS lookup against multiple widely used nameservers around the world.


Use DNS Lookup

Resources for #SeriousSenders


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Seedlist-Based Inbox Monitoring the Right Way

When sending commercial email, it’s important to understand what’s likely to happen the next time you send to a recipient at a particular mailbox provider. Are your messages hitting SPAM at Yahoo! or going missing at Comcast? Are you sacrificing ROI because you lack the proper visibility into performance? Seedlist-based inbox monitoring is a key […]

IP and Domain Warming, a Medieval Perspective

Marketers are often confused about the point of IP and domain warming, and they end up wondering: “Everything is authenticated, and I’m not using a blacklisted IP, so what’s the problem?” In short: senders who blast to their entire list without history look like spammers. Internet service providers (ISPs) can choose what to accept or […]

The Truth About Email Panel Data

We’re often asked about our stance on the use of email panel data. As senders, we want additional data points, visibility, and signals. In a perfect world, email panel data would enable marketers to compare their engagement to that of their competitors within a contextually relevant group of subscribers. Collected ethically and without bias, this […]




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