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Bulk vs. Transactional

⚠️ Since we wrote this blog post more than a decade (!) ago, we've made lots of improvements to Postmark and we now support bulk email sending. Learn more about sending your newsletters, promotional emails, or other marketing emails with Postmark—and see how we keep your bulk email separate from your transactional messages with Broadcast Message Streams.

The most common question we encounter from existing and potential customers is whether a particular email communication is considered bulk or transactional. The following is going to try to break it down. What you’ll see is that there is some gray area, a lot of which is based on content.

Reminder of why we don’t allow bulk #

Postmark was built to help web apps deliver key application emails, which we call transactional email. Legally, these emails don’t require an unsubscribe link. They are also treated differently by the ISPs. When you read any postmaster suggestion for bulk senders, you will see they highly encourage separating bulk and transactional email onto different IPs. There are many reasons for it, a big one is throttling. Sending a bulk campaign followed by a password reset can result in that password email being delayed behind a throttled newsletter.

Examples of emails allowed to be sent with Postmark #

  • Welcome email sent after someone signs up
  • Invoice
  • Comment notification
  • Personal digest - if this is personalized for the individual based on some actions. For example, if your customers want a weekly summary of comments they’ve made or actions they performed.
  • Cancelation email
  • Invite friend tools - you can send to an invitee if your users specifically typed in their address. Any automatic import from an address book generates complaints and should not be used.
  • Individual alerts - like we send when you run out of credits

Examples of emails not allowed to be sent with Postmark #

  • Newsletters
  • Marketing emails
  • Announcements - this includes maintenance notices, site updates, or new features.
  • Bulk welcome emails - those that are sent to everyone at once, such as when a site launches.

How you can tell the difference #

A transactional email is triggered by some action in the application. Usually, it’s the action of the recipient, but can be by some other user like a comment posted on a blog, or an invitation for a friend. A bulk email, on the other hand, has no action except by the people who run the app.

A bulk email is an email that is sent to more than one person that contains the exact same content and is not triggered by an event.

People often ask if customizing some aspect of the email, like the salutation (the Dear ___ line) makes it different content. Or, when the list is fully opt-in, can it be considered transactional. The answer is No, to both. If you can import a list and send an email through an email marketing service, you can’t use Postmark for that email.

If you’re still stuck on whether it’s bulk or not, send us a sample. We’ll be happy to review quickly and give you a thumbs up or down!

Natalie Nagele

Natalie Nagele

Wildbit CEO. Love my kids, travel adventures and parties.