Gmail Promotions Tab: Annotations Preview

Email annotations bring your promotions to life with images, deals, expiration dates and more.

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.


Use DNS Lookup

Resources for #SeriousSenders


Seven design tips and trends email marketers should keep in mind.

*Editor’s Note: We’re super excited to bring you a guest post from Katie White, Associate Director, Travel & Hospitality, Media and Telco at Movable Ink. For more information about Movable Ink, click here.* A picture has always been worth a thousand words, but these days, we’ve entered an era in which visuals are becoming our preferred […]

250ok awarded SOC 2 Type II Certification.

We hope you don’t mind a quick change in our regularly scheduled programming, because we’ve got some super nerdy news to share: We’re incredibly honored to announce the completion of our Service Organization Control (SOC) 2 Type II audit. That’s right, y’all; we’re certified up in here, and we passed with flying colors. What is […]

Prevent mail bombing to protect your reputation.

A new vector of abuse emerged in the email world, one that is hard for any individual brand to catch, but when targeted, the impact on reputation can be serious (Spamhaus-listed serious). It’s known as “mail bombing,” and it is an active and serious threat to both consumers and brands. Why is it so serious? […]




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