HubSpot Marketing Single-send
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For Agents
Trigger a one-off transactional send of an existing HubSpot marketing email to a single recipient with personalisation tokens applied at call time.
Use for: I need to send a one-off marketing email to user@example.com, Trigger a transactional send using an existing HubSpot email template, Send a password-reset style email built as a marketing email, Override the firstName personalisation token at send time
Not supported: Does not send SMS, manage email templates, or update CRM records permanently — use for triggering a one-off send of an existing marketing email only.
The HubSpot Marketing Single-send API delivers a one-off send of an existing marketing email to a single recipient with custom contact properties and personalisation tokens applied at send time. It exposes a single POST endpoint that takes the emailId, recipient, and custom property overrides, returning a send status the caller can log and retry on. Useful for transactional-style triggers where you want HubSpot's marketing email template engine and tracking but without enrolling the contact in a list-based send.
Install Jentic One Beta
Connect the Marketing Single-send to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Marketing Single-send, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with Marketing Single-send API.
Send an existing marketing email to a single recipient identified by email address
Override contact properties at send time so personalisation tokens render with custom values
Pass custom properties to the email template for transactional-style data injection
Reuse HubSpot marketing email templates for transactional sends without rebuilding them
Trigger HubSpot's tracking pixels and link rewriting on a one-off send for engagement reporting
Use Cases
Patterns agents use Marketing Single-send API for, with concrete tasks.
★ Transactional Use of Marketing Templates
Reuse a beautifully designed HubSpot marketing email as a transactional send for events like password resets, order confirmations, or webinar reminders. POST /marketing/v4/email/single-send accepts the emailId of the existing marketing email plus the recipient and custom properties, so design teams maintain templates in HubSpot while engineering triggers the sends from application code.
Call POST /marketing/v4/email/single-send with emailId, message.to=user@example.com, and contactProperties overriding firstName.
Webhook-Triggered Email Drops
Connect a webhook handler (Stripe payment success, new signup) directly to HubSpot single-send so the user receives a branded HubSpot email moments after the trigger event. The single-send endpoint is synchronous from the caller's perspective, returning a send status that the webhook handler can log and retry on transient failures.
On Stripe webhook payment_intent.succeeded, call POST /marketing/v4/email/single-send with emailId and the customer's email address.
Personalisation at Call Time
Inject custom property values into a marketing email template at send time using contactProperties and customProperties on the single-send payload. Personalisation tokens in the template (firstName, orderTotal) render with the values you pass in the request rather than the values stored on the contact record. Useful when the data is request-scoped (a specific order, a specific session) and should not persist to the CRM.
Call POST /marketing/v4/email/single-send with customProperties.orderTotal=49.99 and customProperties.orderId=ord_123 to render the template tokens.
AI Agent Notification Send via Jentic
An AI agent fires a HubSpot-branded notification when a watched condition trips (a customer health score drops, a deal stage changes). The agent searches Jentic for HubSpot single-send, loads the schema for POST /marketing/v4/email/single-send, and executes with the recipient and message body. Jentic isolates the OAuth token so the agent never handles raw credentials and the send takes seconds.
Search Jentic for "send hubspot single email", load the schema for POST /marketing/v4/email/single-send, and execute with emailId and message.to.
Key Endpoints
1 endpoints — the hubspot marketing single-send api delivers a one-off send of an existing marketing email to a single recipient with custom contact properties and personalisation tokens applied at send time.
METHOD
PATH
DESCRIPTION
POST
/marketing/v4/email/single-send
Send a marketing email to a single recipient
POST
/marketing/v4/email/single-send
Send a marketing email to a single recipient
Why Jentic?
Three things that make agents converge on Jentic-routed access.
Credential isolation
HubSpot OAuth and private app tokens are stored encrypted in the Jentic MAXsystem vault. Agents receive scoped execution access — the raw bearer token never enters the agent's context window or logs.
Intent-based discovery
Agents search Jentic with intents like 'send hubspot single email' and Jentic returns the matching operation with its input schema, so the agent calls POST /marketing/v4/email/single-send with the right payload without browsing HubSpot docs.
Time to first call
Direct HubSpot integration: 1 day for OAuth setup, payload shaping, and retry logic. Through Jentic: under 30 minutes — search, load schema, execute.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Marketing Single-send API through Jentic.
What authentication does the Single-send API use?
It accepts HubSpot OAuth 2.0 access tokens or private app tokens (legacy schemes oauth2_legacy and private_apps_legacy), sent as Bearer in the Authorization header. Through Jentic, the token is stored encrypted in MAXsystem and injected at execution time.
Can I send a marketing email to one recipient without enrolling them in a list?
Yes — that is exactly what this API does. POST /marketing/v4/email/single-send takes an emailId and a single recipient, sending one copy without modifying any HubSpot list or workflow enrolment.
How do I override personalisation tokens at send time?
Pass contactProperties (override values for properties on the contact record) and customProperties (per-send values not tied to a contact field) on the request body. Personalisation tokens in the template render with these values for this send only.
What are the rate limits for the Single-send API?
Account-level limits are 100 requests per 10 seconds across HubSpot's authenticated APIs, with daily caps that depend on the subscription tier. Single-send also has its own daily volume cap by tier — check the HubSpot pricing docs for current numbers.
How do I trigger a single send through Jentic?
Run pip install jentic, search for "send hubspot single email", load the schema for POST /marketing/v4/email/single-send, and execute with emailId, message.to, and any contactProperties. Sign up at https://app.jentic.com/sign-up.
Does this endpoint create or modify contact records?
It does not modify the contact record. The contactProperties on the payload only affect the personalisation rendered in this send; permanent updates require the CRM Contacts API.
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