DNS Lookup

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


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"250ok has built a best-of-breed platform that addresses the concerns of today's data-driven marketers."


Len Shneyder
VP of Industry Relations at SendGrid

Hey Sender! See how 250ok can help you monitor DNS issues.



More Free Tools

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


250ok Email Experts Series: How to use email headers.

This is our last video in the Email Experts Series in 2018. To close us out, we’ll look at email headers and how best to use them to your advantage in your marketing email. All episodes in this series are available via mp3 on Soundcloud and Stitcher. You can see all our videos in one […]

GDPR Today and Tomorrow: A conversation with Simon McGarr, a data privacy lawyer.

As with all legislation, there is a certain amount of discomfort, misconceptions, and rumors that start to sound like sage advice as they become repeated, shared, and incorporated into the daily practices of those searching for a guiding light to lead them to compliance. But like a moth drawn to a flame, well-intending practitioners can […]

The Year in Email 2018

The Black Friday emails are deleted, marketers’ email lists are checked twice, we pretty much know which senders have been naughty or nice. Another year in email is coming to a close, and boy, what a ride. While most thought leaders are busy making predictions about 2019, we like to learn from the past to […]




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