canonical: https://jentic.com/apis/hubspot.com/hubspot-marketing-transactional-single-send

# HubSpot Marketing Transactional Single Send

The HubSpot Marketing Transactional Single Send API delivers one-off transactional emails such as receipts, password resets, and account notifications using a HubSpot-designed email template. Senders authenticate either with OAuth or with HubSpot SMTP API tokens that can be created, fetched, and rotated through the same API. The API tracks each send against the standard HubSpot marketing email engagement reporting so transactional opens, clicks, and bounces appear alongside other email activity.

## For AI agents

Send a single transactional email from a HubSpot template and manage the SMTP API tokens used for authenticated delivery.

## Scope

Does not handle bulk marketing campaigns, contact list management, or SMS - use for single-recipient transactional email sends only.

## Capabilities

- Send a transactional email from an existing HubSpot email template with merge field substitutions
- Create a new HubSpot SMTP API token tied to a specific app and campaign for outbound delivery
- List the active SMTP API tokens on a HubSpot portal
- Fetch a specific SMTP API token by token ID to inspect its scope and creator
- Reset the password on an SMTP API token without rotating the token ID itself
- Delete an SMTP API token to revoke outbound transactional sending

## Use cases

### Customer receipt delivery

Send branded order confirmation and receipt emails from a templated HubSpot design at the moment a customer completes checkout. The API substitutes contact properties and custom variables into the template and records the send in HubSpot marketing reports so support teams can see whether the receipt was opened or clicked.

Example prompt: Call POST /marketing/v3/transactional/single-email/send with emailId 12345, the customer's email as the recipient, and orderTotal plus orderNumber as customProperties.

### Password reset and account notifications

Deliver password reset, magic link, and account verification emails through HubSpot using SMTP API tokens scoped to the auth service. The API supports per-message custom properties so the reset link, expiry timestamp, and IP can be merged into the template, and tokens can be rotated by resetting the password without changing the token ID.

Example prompt: Send a password reset email via POST /marketing/v3/transactional/single-email/send using emailId 67890 and a customProperty named resetUrl pointing to the per-user link.

### SMTP token lifecycle management

Provision, audit, and revoke HubSpot SMTP API tokens used by application backends to authenticate outbound transactional mail. Each token is bound to a campaign so reporting attribution stays clean, and tokens can be deleted instantly when an app is decommissioned or a credential leaks.

Example prompt: List active tokens with GET /marketing/v3/transactional/smtp-tokens, identify the leaked token, then call DELETE /marketing/v3/transactional/smtp-tokens/{tokenId} to revoke it.

### Agent-driven transactional sends through Jentic

An AI agent retrieves the send transactional email operation through Jentic's intent search, loads the input schema, and executes a send without ever holding the HubSpot OAuth token in its own context. Jentic handles credential injection so the agent can compose the recipient and template variables and call the operation in a single step.

Example prompt: Through Jentic, search for 'send a transactional email via HubSpot', load the schema for POST /marketing/v3/transactional/single-email/send, and execute it with the customer's email and templated emailId.

## Key endpoints

| Method | Path | Description |
| --- | --- | --- |
| POST | /marketing/v3/transactional/single-email/send | Send a single transactional email from a HubSpot template |
| POST | /marketing/v3/transactional/smtp-tokens | Create a new SMTP API token |
| GET | /marketing/v3/transactional/smtp-tokens | List active SMTP API tokens |
| GET | /marketing/v3/transactional/smtp-tokens/{tokenId} | Retrieve a single SMTP API token |
| POST | /marketing/v3/transactional/smtp-tokens/{tokenId}/password-reset | Reset the password on an SMTP API token |
| DELETE | /marketing/v3/transactional/smtp-tokens/{tokenId} | Delete and revoke an SMTP API token |

## Key resources

- **Single send** — Send a transactional email from a HubSpot template with custom merge properties
- **Public SMTP tokens** — Create, list, fetch, rotate, and delete the SMTP API tokens used for transactional authentication

## Why Jentic

- **Setup:** Wiring HubSpot Transactional Single Send by hand means running its OAuth flow or minting a private-app token, targeting api.hubapi.com, and managing SMTP tokens and per-recipient payloads yourself. Through Jentic you install once, import Marketing Transactional Single Send from the API Directory, store the credential once, and your agent calls it.
- **Permission scoping:** This API puts the SMTP token id in the URL path (/marketing/v3/transactional/smtp-tokens/{tokenId}), so a rule can pin your agent to one SMTP token: it can read that token and nothing else. You choose the operations it may call, so a token deletion or a password reset is not included unless you add it.
- **Credential handling:** Your HubSpot OAuth or private-app token is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.
- **Discovery method:** Agents search Jentic by intent such as 'send a transactional email via HubSpot', and Jentic returns the single-email send operation with its input schema, including the emailId and customProperties shape, so the agent calls the right endpoint without browsing the HubSpot reference docs.

## Related APIs

- **SendGrid Mail Send** — Standalone transactional email provider with higher per-second send limits and dedicated IP options
- **Postmark Server API** — Transactional-only email provider focused on inbox delivery speed and bounce handling
- **HubSpot Marketing Single Send** — Sister HubSpot API for sending marketing emails to a single contact rather than transactional templates
- **HubSpot Marketing Emails** — Manages the underlying email assets and templates that transactional sends reference by emailId

## FAQ

### What authentication does the HubSpot Transactional Single Send API use?

The API accepts HubSpot OAuth 2.0 access tokens or HubSpot private-app tokens passed as a Bearer header. Through Jentic, these credentials live in your encrypted Jentic One instance and are injected at execution time so they never enter the agent's prompt context.

### Can I send password reset emails with the Transactional Single Send API?

Yes. Call POST /marketing/v3/transactional/single-email/send with the emailId of a HubSpot transactional template and pass the reset URL and expiry timestamp as customProperties so they merge into the rendered email.

### What are the rate limits for the HubSpot Transactional Single Send API?

HubSpot's standard public API limits apply: 100 requests per 10 seconds for OAuth apps and 110 requests per 10 seconds for private apps, with a separate transactional email send quota tied to the Marketing Hub subscription tier.

### How do I rotate an SMTP API token through Jentic?

Use the Jentic search query 'rotate HubSpot SMTP token' to find POST /marketing/v3/transactional/smtp-tokens/{tokenId}/password-reset, load its schema, and execute it with the existing tokenId. The token ID stays stable so downstream apps continue to work after the password rotation.

### Does this API support marketing campaign emails or bulk sends?

No. This API sends one transactional email per request and is scoped to single-recipient sends like receipts, password resets, and notifications. For marketing campaign sends, use the HubSpot Marketing Single Send or Marketing Emails API instead.

### Can I delete a leaked SMTP token immediately?

Yes. Call DELETE /marketing/v3/transactional/smtp-tokens/{tokenId} to revoke the token instantly. Any application still using that token will start receiving authentication errors on the next send attempt.

### Can I limit what my agent is allowed to do with the HubSpot Transactional Single Send API?

Yes. Because you run Jentic One yourself, your own rules decide which of this API's operations the agent may call and which credential it uses, so you can allow the single-email send while withholding token deletion or password reset. Since the SMTP token id sits in the URL path (/marketing/v3/transactional/smtp-tokens/{tokenId}), a rule can pin the agent to one token and let it read only that token and nothing else. Operations you do not explicitly grant, such as DELETE on an SMTP token, stay unavailable to the agent.