Postmark Basics

You've already met Resend, SendGrid and Amazon SES, three ways to send email from your app. Postmark is one more service doing the same core job, except it's built around one idea above everything else... getting the emails your users are actually waiting for into their inbox, FAST.

What Postmark Is#

Postmark is an email sending service. Your app talks to it through an API (or through SMTP, the older standard way computers pass email around), and Postmark handles the hard part, which is actually delivering the message.

Postmark calls itself a transactional email service. That word "transactional" matters a lot here, so let's slow down on it for a sec.

Transactional vs Broadcast Email#

An app sends two broad kinds of email.

Transactional email is a one-to-one message that somebody triggered by doing something. Postmark's own description is that transactional email "is typically a unique, high-priority message sent to a single recipient." Here are a few examples.

• A password reset link
• A "confirm your email" message after signup
• An order receipt
• A login code

The person is usually sitting there staring at their inbox waiting for it. If it shows up ten minutes late, or lands in spam, your app feels broken to them.

I've watched what that looks like in real life. A client of mine had 49 form-fill notifications silently disappear after an Outlook update on their end. The sending side said "delivered" every single time... and nothing ever hit the inbox. "Delivered" and "in front of a human" are two VERY different things.

Broadcast email is one message going out to lots of people at once. Newsletters, product announcements and marketing campaigns all live here. Postmark describes broadcast email as email that "is sent to multiple recipients at once."

Message Streams#

Postmark keeps those two kinds of email apart with something called message streams. A message stream is basically a lane that a group of emails travels down.

There are two sending types of stream.

• Transactional streams for one-to-one triggered messages
• Broadcast streams for bulk messages

Postmark says it runs these on separate sending infrastructure, with "Dedicated transactional IPs" and "Separate, parallel broadcast IPs." An IP here is the address of the machine that sends the email. Keeping them apart means a noisy newsletter can't drag down the reputation of your password resets.

Every Postmark server comes with a default Transactional stream. In the API, that stream's ID is outbound. If you send an email and don't say which stream to use, Postmark sends it through that default Transactional stream. You can add a Broadcast stream yourself whenever you need one.

When you send, you pick your lane with a field called MessageStream. For example, "MessageStream": "outbound" sends through the default Transactional stream.

There's also an Inbound stream type, which is for receiving email into your app instead of sending it. You won't need it for a first project.

Servers#

The second idea to get comfy with is the server. In Postmark, a server isn't a physical computer you have to babysit. Postmark's documentation calls servers "a way to organize the emails that you are sending or parsing."

The easiest way to picture a server is as a folder for one project. Postmark gives these example uses.

• Separating environments, like one server for staging and one for production
• Separating different clients
• Separating different applications

Each server gets its own API token (the secret key your code uses to send), and its activity and stats are tracked separately. So if you build two apps, giving each one its own server keeps their emails, stats and keys from getting tangled up.

Message streams live inside a server. Put together, the full picture looks like this.

Your Postmark account
  Server: my-app-production
    Stream: outbound (Transactional, the default)
    Stream: a Broadcast stream you add later
  Server: my-app-staging
    Stream: outbound (Transactional, the default)

New Accounts Are Reviewed#

Postmark manually reviews every new account before it can send to anybody. Until your account's approved, you can only send to email addresses on the domains you've added to your account and verified.

Postmark says the review gets done "in less than 24 hours on weekdays and a little longer on the weekends." While you wait you can still use the API, build templates, try out webhooks and send test emails to your own verified domain. You can also send to Postmark's test address, [email protected]. Anything sent there gets dropped on the receiving end, but you can still see it in your Activity.

Pricing#

Postmark's pricing page says every new account starts on a free developer plan with 100 emails per month, and that plan doesn't expire. That's plenty to build and test with, but it won't cover a real app with real users.

Paid plans are priced by how many emails you send each month. Prices change over time, so check the pricing page for current numbers before you pick a plan.

When to Pick Postmark#

Postmark and Resend can both send your app's emails. So how do you choose? Here's a plain way to think about it.

Postmark is a good fit in these cases.

• Your most important emails are transactional, like password resets, login codes and receipts
• You want transactional and marketing email kept on separate infrastructure by design
• You want a clean way to organize several projects or environments, using servers

If you've already got Resend working and you're happy with it, there's no need to switch. Neither choice is forever, either. Both are reached through an API, so switching later mostly means changing the handful of lines of code that send mail.

TL;DR#

• Postmark is an email sending service focused on transactional email, the one-to-one messages users sit there waiting for
• Transactional email goes to one person because of something they did, while broadcast email goes to lots of people at once
• Message streams keep transactional and broadcast email on separate infrastructure so one can't hurt the other
• The default Transactional stream has the ID outbound, and you choose a stream with the MessageStream field
• A server is a folder for one project or environment, with its own API token and stats
• New accounts get reviewed before they can send outside your own verified domains
• The free developer plan includes 100 emails per month

What's Next?#

In the next lesson you'll set up a Postmark account, create a server, verify your domain and send your very first email from Node...