Postmark is an email delivery service that enables developers to send transactional emails with high deliverability and detailed analytics.
Postmark is an email delivery service that enables developers to send transactional emails with high deliverability and detailed analytics. On Nagent, Postmark is exposed as a fully-configurable transactional email integration that any agent can call — 46 actions, and API key authentication. No code is required to wire Postmark into your workflow — connect it once via the External Integrations panel and reuse it across every agent you build.
Agent builders use Postmark to automate the kinds of tasks transactional email teams previously handled manually. Concrete examples — each one is a single agent step in Nagent — include:
Every action and trigger is paired with a structured input/output schema (visible in the sections below), so when you wire Postmark into Helix — our agentic agent builder — the editor knows exactly what each step expects and produces. Configure once, deploy anywhere across your Nagent agents.
Every operation an agent can call against Postmark, with input parameters and output schema. Drop these into any step of an agent built in Helix.
POSTMARK_ARCHIVE_MESSAGE_STREAMTool to archive a message stream (soft delete). Use when you need to remove a message stream that will be permanently deleted after 45 days.
Input parameters
The ID of the message stream to archive
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_CHECK_SPAM_SCORETool to assess the spam score of a raw email via the SpamCheck API. Use when you have full email source and need spam scoring before sending. Returns spam score and detailed report.
Input parameters
Full raw email source to analyze for spam scoring
Detail level of the report: 'short', 'long', or 'summary'. Defaults to 'short'.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_CREATE_INBOUND_RULETool to create a new inbound rule trigger to block email from a specific sender or domain. Use when you need to prevent emails from specific addresses or domains from being processed.
Input parameters
Email address or domain to block from inbound messages (e.g., 'spam@example.com' or 'baddomain.com')
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_CREATE_MESSAGE_STREAMTool to create a new message stream. Use when you need to set up separate streams for transactional or broadcast emails.
Input parameters
The stream identifier (e.g., 'transactional-dev'). Must be unique within the server.
The name of the message stream
A description of the message stream
The type of stream: either 'Transactional' for transactional emails or 'Broadcasts' for marketing emails
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_CREATE_SUPPRESSIONSTool to add email addresses to the suppression list for a message stream. Use when you need to prevent emails from being sent to specific addresses.
Input parameters
The message stream ID (e.g., 'outbound', 'broadcast')
Array of email addresses to suppress (max 50 per request)
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_CREATE_TEMPLATETool to create a new email template. Use when you need reusable templates before sending emails.
Input parameters
Template name (max 255 characters)
Unique template alias (max 100 characters)
Template subject line, can include variables, e.g., {{name}}
HTML content of the template
Plain text content of the template
Type of the template: 'Standard' or 'Layout'
Alias or ID of a layout template (required for Standard templates using a layout)
Server ID to associate this template with
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_CREATE_WEBHOOKTool to create a new webhook configuration for Postmark. Use when you need to set up a webhook to receive event notifications for email tracking (opens, clicks, bounces, deliveries, etc.).
Input parameters
The webhook URL endpoint where events will be sent.
HTTP authentication credentials for the webhook endpoint.
Defines which events trigger this webhook.
Optional array of custom headers to include in webhook requests.
The message stream for this webhook (e.g., 'outbound', 'inbound'). Defaults to 'outbound' if not specified.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_DELETE_INBOUND_RULETool to delete a specific inbound rule trigger. Use when you need to remove an inbound rule by its ID after confirming it's no longer needed.
Input parameters
The ID of the Inbound Rule that should be deleted.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_DELETE_SUPPRESSIONSTool to remove email addresses from the suppression list for a message stream. Use when you need to reactivate previously suppressed email addresses. Note that only HardBounce and ManualSuppression types can be deleted; SpamComplaint suppressions cannot be removed.
Input parameters
The unique identifier for the Message Stream (e.g., 'outbound', 'inbound')
Array of email addresses to remove from suppression list (maximum 50 per request). Note: SpamComplaint suppressions cannot be deleted, only HardBounce and ManualSuppression types can be removed.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_DELETE_TEMPLATETool to delete a template by its ID or alias. Use when you need to permanently remove a template after confirming it's no longer needed.
Input parameters
The TemplateID (numeric) or Alias (string) value for the template you wish to delete
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_DELETE_WEBHOOKTool to delete a specific webhook. Use when you need to remove a webhook by its ID after confirming it's no longer needed.
Input parameters
ID of the webhook to delete
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_EDIT_SERVERTool to update settings for the current Postmark server. Use when you need to modify server configuration.
Input parameters
Name of the server.
Hex color code for the server, e.g., '#FF0000'.
URL to POST open webhook events.
URL to POST bounce webhook events.
Domain to handle inbound emails.
URL to POST inbound email webhook events.
URL to POST delivery webhook events.
Enable or disable raw email support.
Enable or disable SMTP API for the server.
Send open webhook only on the first open event.
Spam score threshold for inbound email, must be non-negative.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_EDIT_TEMPLATETool to update an existing Postmark template by its ID. Use when you need to modify a template's name, subject, HTML or text body, alias, type, layout, or active status.
Input parameters
New name for the template
Alias for easier lookup of the template
Whether the template should be active (true) or inactive (false)
Subject line for the template
HTML body content of the template
Plain-text body content of the template
The unique ID of the template to update
Type of template; either 'Standard' or 'Layout'
Alias of a layout template to wrap this template with (for Standard templates)
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_EDIT_WEBHOOKTool to update an existing webhook’s URL or triggers. Use when you need to modify webhook settings after confirming the webhookID.
Input parameters
The URL to receive webhook POSTs
Event triggers for the webhook; keys are event names, values indicate if enabled
Optional secret token for authenticating webhook calls
ID of the webhook to update
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_BOUNCE_COUNTSTool to get total counts of emails that have been returned as bounced. Use when you need aggregate bounce statistics and per-day breakdown by bounce type (hard bounce, soft bounce, transient, SMTP API errors).
Input parameters
Filter bounce statistics by a specific tag.
Filter stats up to this date (YYYY-MM-DD format).
Filter stats starting from this date (YYYY-MM-DD format).
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_BOUNCESTool to retrieve a list of bounces for a server with optional filters. Use when you need to page through bounce data after applying filters.
Input parameters
Filter bounces sent with this tag.
Filter by bounce type. Exact match, e.g., 'HardBounce', 'Transient', 'SoftBounce', 'SpamComplaint'.
Number of bounces to return per page (1-500).
Number of bounces to skip for pagination.
Only include bounces before this ISO-8601 datetime.
Only include bounces after this ISO-8601 datetime.
If true, return only inactive bounces.
Return bounces for this specific message ID.
Return bounces for this specific email address.
Filter by mailbox hash (the part after '+' in the email).
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_BROWSER_PLATFORM_USAGETool to retrieve browser platform usage statistics for clicked links. Use after sending outbound emails with tracked links to analyze engagement by browser.
Input parameters
Optional filter by tag to narrow down statistics to specific emails
Filter end date (inclusive) in YYYY-MM-DD format, e.g., '2024-02-01'
Filter starting date (inclusive) in YYYY-MM-DD format, e.g., '2024-01-01'
Optional filter by message stream; includes all streams if omitted
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_BROWSER_USAGETool to retrieve browser usage statistics for clicked links. Use after sending tracked outbound emails to analyze which browsers and platforms were used to click links.
Input parameters
End date for stats range in YYYY-MM-DD format.
Start date for stats range in YYYY-MM-DD format.
Filter stats by server id (optional)
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_CLICK_COUNTSTool to retrieve total click counts across all links in emails. Use when you need aggregated click metrics for a given date range.
Input parameters
Filter by operating system.
Filter by specific tag.
End date for stats range in YYYY-MM-DD format.
Filter by country code.
Start date for stats range in YYYY-MM-DD format.
Filter by client platform.
Filter by client name.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_CLICKS_BY_BROWSER_FAMILYTool to retrieve click statistics grouped by browser family. Use after sending outbound emails with tracked links to analyze which browser families recipients used to click links. Requires link tracking to be enabled for emails.
Input parameters
Filter by specific tag to narrow down statistics to emails with this tag
Filter end date (inclusive) in YYYY-MM-DD format
Filter starting date (inclusive) in YYYY-MM-DD format
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_CLICKS_BY_LOCATIONTool to get an overview of which part of the email links were clicked from (HTML or Text). Use when you need to analyze click patterns by content type.
Input parameters
Filter by tag.
Filter stats up to the date specified in YYYY-MM-DD format.
Filter stats starting from the date specified in YYYY-MM-DD format.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_DELIVERY_STATSTool to retrieve delivery statistics. Use after sending emails to get aggregated counts of deliveries, bounces, and spam complaints.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_EMAIL_CLIENT_USAGETool to retrieve statistics on email clients used to open emails. Use when you need to analyze which clients recipients open your outbound emails.
Input parameters
Filter by tag name (if emails were sent with a tag)
End date for the statistics (inclusive, format: YYYY-MM-DD)
Start date for the statistics (inclusive, format: YYYY-MM-DD)
Filter by message stream ID. If omitted, returns stats for all server streams.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_EMAIL_OPEN_COUNTSTool to retrieve counts of opened emails. Use when you need per-day and total open stats for a specified period.
Input parameters
Include activity before this ISO8601 date/time.
Include activity from this ISO8601 date/time.
Filter stats by a specific message stream.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_MESSAGE_STREAMTool to retrieve details of a specific message stream by its ID. Use when you need to inspect stream configuration such as type, description, or subscription settings.
Input parameters
The ID of the message stream to retrieve (e.g., 'outbound', 'inbound', or custom stream ID)
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_OPENS_BY_PLATFORMTool to retrieve email open statistics by platform type. Use when you need to understand which platforms recipients use to open emails.
Input parameters
Filter by tag to narrow down statistics to specific emails
Filter end date (inclusive) in YYYY-MM-DD format, e.g., '2014-02-01'
Filter starting date (inclusive) in YYYY-MM-DD format, e.g., '2014-01-01'
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_OUTBOUND_OVERVIEWTool to retrieve outbound email statistics overview. Use when you need aggregated outbound metrics after sending emails.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_SENT_COUNTSTool to retrieve total count of emails sent out. Use when you need per-day and total sent statistics for a specified period.
Input parameters
Filter by specific tag to get sent counts for emails with that tag.
End date for stats range in YYYY-MM-DD format. If not provided, defaults to today.
Start date for stats range in YYYY-MM-DD format. If not provided, defaults to 30 days ago.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_SERVERTool to retrieve details of the current Postmark server. Use when you need to inspect server configuration (webhooks, tracking, tokens, etc.) before other operations.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_SPAM_COMPLAINTSTool to retrieve counts of spam complaints. Use when analyzing spam feedback trends after sending campaigns.
Input parameters
Filter by tag associated with emails
Filter stats up to and including this date (YYYY-MM-DD format)
Filter stats starting from this date (YYYY-MM-DD format)
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_TEMPLATETool to retrieve details of a specific template by its ID. Use after obtaining a template ID to inspect its configuration.
Input parameters
The unique numeric ID of the template to retrieve
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_TRACKED_EMAIL_COUNTSTool to retrieve counts of emails with tracking enabled. Use after specifying a date range to analyze open and click metrics.
Input parameters
End date of the tracking period in YYYY-MM-DD format
Start date of the tracking period in YYYY-MM-DD format
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_GET_WEBHOOKTool to retrieve details of a specific webhook by its ID. Use when you need to inspect webhook configuration including URL, triggers, and message stream settings.
Input parameters
The unique identifier of the webhook to retrieve
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_LIST_INBOUND_RULESTool to list all inbound rules (triggers) configured for blocking senders. Use when you need to retrieve configured inbound rules with pagination support.
Input parameters
Number of inbound rules to return per page. Required by the API.
Number of inbound rules to skip for pagination. Required by the API.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_LIST_MESSAGE_STREAMSTool to list all message streams for a Postmark server with optional type and archive filtering. Use when you need to retrieve available message streams. A server may have up to 10 streams including defaults.
Input parameters
Message stream type options for filtering.
Include archived streams in the response.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_LIST_OUTBOUND_MESSAGE_CLICKSTool to list clicks for outbound messages with filtering options. Use when you need to retrieve click events with pagination and optional filters like recipient, tag, client, OS, platform, or geographic location.
Input parameters
Filter by tag associated with the message.
Filter by full name of city messages were clicked in, e.g. Moscow, New York.
Number of message clicks to return per request. Max 500.
Number of messages to skip for pagination.
Filter by full name of region messages were clicked in, e.g. Moscow, New York.
Filter by country messages were clicked in, e.g. Denmark, Russia.
Filter by full OS name and specific version, e.g. OS X 10.9 Mavericks, Windows 7.
Filter by platform, e.g. webmail, desktop, mobile.
Filter by kind of OS used without specific version, e.g. OS X, Windows.
Filter by To, Cc, or Bcc recipient email address.
Filter by company which produced the OS, e.g. Apple Computer, Inc., Microsoft Corporation.
Filter by client name, e.g. Outlook, Gmail.
Filter by client family, e.g. OS X, Chrome.
Filter by company that makes the client, e.g. Microsoft, Apple, Google.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_LIST_OUTBOUND_MESSAGE_OPENSTool to retrieve opens for outbound messages with filtering options. Use when you need to analyze email open events with detailed client, OS, and geographic data.
Input parameters
Filter by message tag.
Filter by city where messages were opened, e.g., Moscow, New York, San Francisco.
Number of message opens to return per request. Max 500.
Number of messages to skip for pagination.
Filter by full name of region where messages were opened, e.g., Moscow, New York, California.
Filter by country where messages were opened, e.g., Denmark, Russia, United States.
Filter by full OS name and specific version, e.g., OS X 10.9 Mavericks, Windows 7.
Filter by platform type, e.g., webmail, desktop, mobile.
Filter by kind of OS used without specific version, e.g., OS X, Windows, Linux.
Filter by To, Cc, or Bcc recipient email address.
Filter by company which produced the OS, e.g., Apple Computer, Inc., Microsoft Corporation.
Filter by client name, e.g., Outlook, Gmail, Chrome.
Filter by client family, e.g., OS X, Chrome, Firefox.
Filter by client company, e.g., Microsoft, Apple, Google.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_LIST_SUPPRESSIONSTool to retrieve the suppression list for a message stream with optional filtering. Use when you need to view all suppressed email addresses for a stream.
Input parameters
Source of the suppression entry.
Include suppressions up to this date (format: YYYY-MM-DD, e.g., 2020-02-01)
Include suppressions from this date onwards (format: YYYY-MM-DD, e.g., 2020-02-01)
The message stream ID to retrieve suppressions from (e.g., 'outbound', 'broadcast')
Filter results by specific email address
Reason for email suppression.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_LIST_TEMPLATESTool to list all templates for a Postmark server. Use when you need to retrieve available templates with optional pagination and filters.
Input parameters
Number of templates to return per page (1-500). Required by the API.
Number of templates to skip for pagination. Required by the API.
Filter templates by type: 'Layout' or 'Standard'.
Filter templates by statuses: 'true', 'false', or 'true,false'.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_LIST_WEBHOOKSTool to list all webhooks configured for your Postmark account. Use after authenticating your server token to retrieve current webhook configurations.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_SEARCH_INBOUND_MESSAGESTool to search inbound messages received with optional filtering. Use when you need to retrieve inbound emails with pagination and various filters.
Input parameters
Filter by tag.
Number of messages to return per request. Max 500.
Number of messages to skip for pagination.
Status values for inbound messages.
Filter messages up to the date specified. e.g. '2014-02-01'
Filter by email subject.
Filter messages starting from the date specified. e.g. '2014-02-01'
Filter by the sender email address.
Filter by the user who was receiving the email.
Filter by mailbox hash.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_SEARCH_OUTBOUND_MESSAGESTool to search outbound messages with filtering by recipient, tag, status, and date range. Use when you need to query sent messages with specific filters or pagination.
Input parameters
Filter by tag.
Number of messages to return per request. Max 500. Required by the API.
Number of messages to skip for pagination. Required by the API.
Status of an outbound message.
Filter messages up to the date specified. Format: YYYY-MM-DD (e.g. 2014-02-01).
Filter messages starting from the date specified. Format: YYYY-MM-DD (e.g. 2014-02-01).
Filter by the sender email address.
Filter by the user who was receiving the email.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_SEND_BATCH_WITH_TEMPLATESTool to send multiple templated emails in a single batch API call. Use when you need to send up to 500 templated messages at once.
Input parameters
List of templated messages to send (max 500)
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_UNARCHIVE_MESSAGE_STREAMTool to unarchive a previously archived message stream. Use when you need to restore an archived stream (within 45 days of archiving).
Input parameters
The ID of the message stream to unarchive. Must be archived within the last 45 days.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_UPDATE_MESSAGE_STREAMTool to update a message stream configuration in Postmark. Use when you need to modify a stream's name or description. Note that stream type and ID cannot be changed after creation.
Input parameters
The name of the message stream
The ID of the message stream to update
The description of the message stream
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
POSTMARK_VALIDATE_TEMPLATETool to validate a Postmark template. Use when checking that a template's subject and body render correctly against sample data.
Input parameters
The subject line of the template.
The HTML content of the template.
The plain-text content of the template.
Type of the template, either 'Standard' or 'Layout'.
Mock data used to render and validate the template.
Output
Data from the action execution
Error if any occurred during the execution of the action
Whether or not the action execution was successful or not
No publicly available marketplace agent is found using this tool yet. There are 45 agents privately built on Nagent that already use Postmark.
Build on Nagent
Connect Postmark to any Nagent agent in minutes — no API key management, no boilerplate. Just configure and deploy.
The five questions agent builders ask before adopting a new integration.
Open the External Integrations panel inside Nagent (app.nagent.ai/externalIntegration), find Postmark, and click "Connect Now." You'll authenticate with an API key — Nagent handles credential storage and refresh automatically. Once connected, Postmark is available to any agent in your workspace.
No. Nagent provides no-code integration for every tool. Once Postmark is connected, you configure its 46 actions directly in the agent builder UI — no API calls, no boilerplate, no schema management.
Helix — Nagent's agentic agent builder — lets you drop Postmark steps into any workflow visually. Pick an action (e.g., one of those listed above), fill in the inputs (Helix knows the required vs. optional schema for each parameter), and connect it to upstream/downstream steps. Triggers run as the entry point of an agent, so when a Postmark event fires, the agent kicks off automatically.
Every Postmark action and trigger ships with a fully-typed schema — input parameters with name, type, required flag, and description, plus the output payload shape. The schemas are documented in the sections above. Helix uses these schemas to validate your configuration at build time and to type-check the data flowing between steps.
Yes. While Postmark ships with 46 pre-built transactional email actions, you can layer custom logic around them inside Helix — pre/post-processing steps, conditional branches, retries, or stitching Postmark together with other connected tools. For deeper customization, talk to our team about Nagent's Agentic AI Lab — forward-deployed engineers who build Postmark-based workflows tailored to your business.