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A better way to send all your application email.

Message Streams optimize deliverability for all email: transactional, broadcast, and everything in between.


Postmark is no longer for transactional email only.

Over the last nine years, we’ve established a reputation as the fastest and most reliable provider for your transactional email. We also know that the lines between transactional and broadcast email can be fuzzy. That’s why we've invested in making Postmark the most reliable provider for all your application-based email.

Our goal is to fill in the gaps we see between transactional and other types of application email and be able to send messages that need to go out to multiple recipients at once.

Traditionally we rejected all messages like this, which caused many of our customers to split their messages across multiple providers. By accepting more of these high-quality, high-engagement messages, we can eliminate the need to use multiple providers and make life easier.

Separate streams to protect transactional and broadcast messages.

Whether your email makes it to the inbox quickly and consistently depends on a lot of things, including what and how you send.

In the past, Postmark optimized deliverability and time-to-inbox by restricting the email sent through our infrastructure to transactional only.

But transactional messages aren’t the only type of application email that support great user experiences. Product update announcements and updates to your terms of service are also important. So we set out to make sure Postmark could support all types of messages, regardless of how they were sent.

Message Streams provide a way to route different types of email so that they all maintain optimal deliverability. Just let us know what type of email will be sent—whether it’s transactional or broadcast—and we’ll take it from there.

Proven deliverability and reliability.

Our mission is to make email painless and enjoyable for product development teams.

Because different types of email have various origins as well as vulnerabilities, we have always recommended separating transactional traffic from other types of email by using different sending IPs and From domains. Following our own advice, we have created a separate, but parallel, infrastructure for these two types of email.

This puts us in the unique position to both preserve our world-class transactional service and superior deliverability while using that experience to build the ultimate sending environment for all your application email.

That means transactional and broadcast traffic do not mix in Postmark, including IP ranges. This follows best practices for separating email reputation as recommended by inbox providers like Gmail.


What is Message Streams?

Messages Streams from Postmark is a better way to send your application email.

Each Message Stream is classified based on how your email is sent: transactional (sent to a single recipient) or broadcast (sent to multiple recipients). That classification helps us group and route emails into the right sending IPs to optimize deliverability and time to inbox.

That’s because unlike other email infrastructure providers, we don’t use the same infrastructure to send all types of email. Instead, we run parallel but separate sending infrastructures. That ensures that broadcast and transactional traffic don’t mix in Postmark, following sending best practices established by inbox providers like Gmail.

You can have up to 10 Streams in a server which can help separate and organize your sending within an individual server.

I thought Postmark was for transactional email only. Why change?

Expectations for application email have evolved. Today’s customers demand (and deserve!) a great user experience from your website or web app. But transactional messages aren’t the only type of application email that support great user experiences. App updates, release notes, daily digests, event invitations, and more are also used to deliver the best possible experience with a product or service.

That’s fundamentally why we created Postmark: to help product development teams communicate with their customers reliably and effectively. But we can’t do that if Postmark is limited to only one kind of application email.

The introduction of Message Streams helps us offer a better way to integrate email into your web apps. So you can use Postmark to send all your application email—both broadcast and transactional.

How will you maintain high deliverability?

Separating transactional traffic from other types of email using different sending IPs and From domains is a longstanding best practice for ensuring optimal deliverability. Different types of email have entirely different origins as well as vulnerabilities. Grouping similar types of emails together while keeping sending environments as distinct as possible helps inbox providers recognize what’s safe to place in the inbox.

We know that expanding the type of email you can send through Postmark is important to our customers. So is maintaining the industry-leading deliverability and time-to-inbox Postmark is known for. That’s why we created an entirely new sending infrastructure to support broadcast messages: one that is parallel to our transactional email infrastructure, but completely separate.

Message Streams enable Postmark users to route emails through the appropriate sending infrastructure based on how they’re sent. That means transactional and broadcast traffic never intersect in Postmark, including IP ranges. We’re proud to say that makes Postmark the only major email API provider adhering to the email traffic management standard promoted by the world’s most popular inbox providers, including Gmail.

Can any sender use Postmark now?

Postmark will never be an open door to any sender. We’re still manually vetting each potential customer, chatting with them one-on-one about what they send and why. Unlike some other providers who accept almost anyone who will hand them money or free data, we’re dedicated to supporting only senders who follow and exceed best practices.

Just in case someone is especially clever at hiding their intentions, we’ve also built internal anti-abuse systems that not only help us analyze all senders’ performance but can also stop potentially spammy messages before they’re sent.

Investing in Message Streams and expanding the type of email sent through Postmark has given us even more opportunities to build and improve the systems that preserve our exceptional deliverability and high standing with receiving ISPs.

What’s the difference between transactional and broadcast?

Transactional email is typically a unique, high-priority message sent to a single recipient. They are often triggered by something a user does or doesn’t do. Broadcast email, on the other hand, is sent to multiple recipients at once. Things like product update announcements or terms of service notices are examples of broadcast emails.

Can I use Postmark to send marketing or promotional campaigns?

Postmark is built for application email. That means that we don’t offer some of the features you might want if you were sending traditional marketing campaigns, including support for list uploads, a WYSIWYG editor, and campaign-based reporting.

It’s true that we’re no longer restricting use of Postmark based on what type of email you’re sending (unless it’s spam!). Our focus remains the same: supporting product development teams.

Message Streams can help you easily integrate email into your apps, reliably deliver that email, and quickly diagnose any issues. So if you choose to use Postmark for things like marketing campaigns or newsletters, you’ll still need to send those messages via your application.

If your needs are less about supporting application-based sending and more around enabling marketing promotion, there are other tools that may be a better fit for you than Postmark.

Do you support list management?

We’re creating tools for managing unsubscribes and suppression lists, but you’ll need to continue managing your main email lists outside of Postmark. You can keep your lists in-sync with Postmark using a new unsubscribe webhook.

How much does it cost to send broadcast emails with Postmark?

There are no additional add-ons or fees to send broadcast messages. Any email you send through Postmark will count towards the monthly email limit for your subscription plan, just like transactional and inbound messages. For more information on our subscription plans, check out our pricing page.

For existing customers using our legacy credits pricing, each message will consume one credit.

How do I get started?

Are you an existing Postmark customer? Broadcast Message Streams are available in your Postmark account, and you can start sending right away! Read our step-by-step guide on how to get set up and start sending and watch our support video on how Message Streams work.

If you're new to Postmark, start a free trial to take Message Streams (and everything else we have to offer) for a spin. When you’re ready to start sending Broadcast emails, just request approval, and we’ll take it from there!