Issue with Transactional Email API – Missing transactional-email Scope

Develop, Build & Integrate APIs & Integrations
1

Hi HubSpot Support Team,

I am facing an issue while testing the HubSpot Transactional Email API.

Account details:

HubSpot Account Name: LAB DE Sandbox neu (03-2026)
Account Type: Sandbox / Developer Test Account
Account Login Email: vivek.gupta@pon.com
Private App: LAB DE Sandbox neu private app

Scopes set for the Private App:

crm.schemas.companies.write
crm.schemas.contacts.write
content
marketing-email
transactional-email
crm.objects.contacts.write
crm.objects.marketing_events.read
crm.objects.marketing_events.write
crm.objects.companies.write
crm.objects.companies.read
crm.schemas.contacts.read
crm.objects.contacts.read
crm.schemas.companies.read

Setup details:

  • Private App is created with the required scopes, including transactional-email.
  • I am able to create contacts successfully via API.
  • I am able to retrieve email templates through API.
  • Email templates are currently created under Marketing > Email.

Issue:

When trying to send an email using the Transactional Email API endpoint, I receive a 403 error:

Status: error
Message: This app hasn’t been granted all required scopes to make this call.
Required scope: transactional-email
Category: MISSING_SCOPES

API endpoint used:

/marketing/transactional/2026-03/single-email/send

I have already added the transactional-email scope to the Private App, but the error still occurs.

Could you please help clarify the following?

  1. Is an additional Transactional Email add-on or entitlement required for this API?
  2. Are Sandbox / Developer Test accounts allowed to use the Transactional Email API?
  3. Am I creating the templates in the correct location, Marketing > Email, or is a different setup required for transactional emails?
  4. Is my current approach correct, or is there any account-level setting missing?

Please let me know the possible reason why this is failing.

Thank you for your support.

Regards,
Vivek Gupta

2

Hi @VGupta39,

The short answer is: the transactional-email scope alone isn’t enough. Your HubSpot account also needs the Transactional Email add-on enabled at the account level.
Even if the scope is checked in your Private App settings, it can’t be fully granted without that underlying entitlement, which is why you’re hitting the 403 MISSING_SCOPES error despite having done everything right on the app side.

To answer your questions directly:

1. Yes, the add-on is required. The Transactional Email API is gated behind the transactional email add-on. This is almost certainly the root cause here.

2. Sandbox accounts don’t include paid add-ons by default. Standard sandbox and developer test accounts won’t inherit things like the transactional email add-on. If you need to test this properly, look into using a test account; these let you simulate specific subscription tiers and add-ons without needing a live paid account.

3. Template type matters - Transactional emails need to be created as the Transactional email type in the HubSpot email tool, not as a standard marketing email. Once published, you pass that template’s `emailId` to the send endpoint. So if you’ve been building them under the regular Marketing > Email flow without setting the type to Transactional, that’s worth double-checking too.

4. Nothing wrong with your app setup - it sounds like you’ve done that part correctly. The missing piece is the account-level add-on.

Hope that helps!
Cassie, Community Manager