The 250ok Advantage

From stronger coverage to a best-practice approach to seed testing, you gain an advantage when using 250ok Inbox.

Optimized Seed Testing

Seedlist Optimizer (patent pending) enables you to weigh your results based on the composition of your email lists. Stop testing providers you don't mail to.

Learn more about Seedlist Optimizer

Automated Monitoring & Alerts

Live outside the app with custom email, SMS, Slack, HipChat, PagerDuty, and webhook alerts. Set it and forget it. Focus on what matters to you, free of pointless notifications.

Learn more about 250ok Alerts



Comprehensive Coverage

Enjoy 250ok's unparalleled coverage of B2B and B2C mailbox providers around the globe. Track your inbox placement and deliverability in real time to pinpoint and resolve issues.



Expert Services & Support

You won't find any junior-level script readers here. Ask for examples of deliverability issues 250ok diagnosed, triaged, and quickly resolved after other competitors failed.

Learn more about 250ok Experts

Why use seedlist testing?

Seedlist testing reveals if your mail is passing global filters at Gmail, Microsoft, Yahoo/AOL, and all other providers.

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 data point in solving this issue.

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Do you need email certification and panel data?

Old-school solutions to modern challenges are not a recipe for success. That's why we love debunking sender mythology — so you don't get burned.


Myth #1: Everyone Needs Email Panel Data!

No, everyone sending commercial email today already owns the most relevant panel in the world: the people they're sending mail to. With currently available panel offerings there is no statistical significance for most senders and the data is often misleading and hazardous given its severe biases.

Myth #2: Email Certification is a Smart Investment!

For most senders – not all – the juice is no longer worth the squeeze. Cert won't help you at Gmail, the largest mailbox provider in the world. Based on changes in the modern email landscape, 250ok customers combine best practices with expert services to achieve world-class performance.

Myth #3: Seedlist-based Inbox Testing is Dead!

While some vendors downplay the value of seedlist testing, do so at your own peril. Seeds are like spam traps: by the time the red flag goes up, there's already a problem. They are a critical component in testing perimeter defenses like blacklists, global spam filters, and reputation in general.

Resources for #SeriousSenders


250ok now powers two-thirds of the top 6 US e-retailers.

You read that right. We are so excited to announce 250ok now brings advanced email analytics to supercharge the email programs of four of the top six US retail ecommerce companies by sales share (as of September 2018), according to eMarketer. What does this mean for you? Oh, only that we’re a trusted partner for […]

Email Mythbusters: Changing my IPs and/or domain will fix my reputation issues.

Imagine… You are welcoming guests into your home for a party. As people start to file in, you greet them with smiles and hugs, exchanging hellos and kind words. There is your best friend who, thankfully, brought wine and dessert. You greet your co-worker, too, and briefly chat about the weather. As you get ready […]

Email Validation 102: Pros and Cons

We’re back with our next blog in our partnership with Lauren Meyer, Mailjet’s global VP of delivery & head of operations, North America. What are the things you should expect to encounter, positive and negative, when you start cleaning your email marketing lists via validation? Considerations for the Marketer If you checked out “Email Validation […]




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