Postmark integration

Postmark is an email delivery service focused on transactional email. This integration lets your WeWeb backend send emails using Postmark’s API.

Use cases

• Send transactional emails from backend workflows (sign-up confirmations, password resets, receipts)
• Use plain text, HTML, or both (multipart)
• Add attachments, CC/BCC, tags, and custom metadata for tracking
• Track opens and link clicks when enabled

Setup

1. In Postmark, create a Server and obtain an API Token (My Server → API Tokens).
2. In WeWeb, go to the Settings tab → Integrations → Postmark → Add connection.
3. Add your API Token for each environment (Editor, Staging, Production) as needed.
4. Verify your Sender Signature (email or domain) in Postmark so you can send from your chosen From address.
5. Test by sending a simple email (e.g. to yourself) using the Send Email action.

Common pitfalls (setup & usage)

Sender not verified

The From email or domain must be verified in Postmark. Use the Sender Signatures section in the Postmark dashboard to verify. Until then, sends may fail or be restricted.

Text content required

You must provide at least Text Content (TextBody). Provide both Text Content and HTML Content for multipart messages; total size cannot exceed 50 MB.

50-recipient limit

To, Cc, and Bcc combined are limited to 50 recipients per message. Split larger sends into multiple API calls.

Webhook / Message stream

If you use multiple message streams, set MessageStream to the correct stream ID (e.g. outbound transactional). Default is the outbound transactional stream.

All Actions

Action	Description
Send Email	Send an email with optional HTML, attachments, CC/BCC, tag, and metadata

Action details

Send Email

Send a single email through Postmark. At least Text Content is required; HTML Content is optional. Attachments, CC/BCC, tag, metadata, and tracking options are supported.

Inputs

Display Key	Example Input	Description	Restrictions
From Email	"sender@example.com"	Sender address (must be from a verified email or domain)	Required
To Email(s)	"recipient@example.com"	Recipient address(es), comma-separated (max 50 total with Cc/Bcc)	Required
Subject	"Your order confirmation"	Email subject	Required; max 1000 chars
Text Content	"Thank you for your order."	Plain text body	Required; provide both for multipart
HTML Content Optional	"<p>Thank you...</p>"	HTML body	Multipart when both text and HTML provided; max 50 MB total
Attachments Optional	[{ "Name": "doc.pdf", "Content": "<base64>", "ContentType": "application/pdf" }]	File attachments; each needs Name, Content (Base64), ContentType; optional ContentID for inline images	Total email size max 50 MB
Reply To Optional	"support@example.com"	Reply-to address	—
CC Recipients Optional	"cc@example.com"	Carbon copy, comma-separated	Counts toward 50-recipient limit
BCC Recipients Optional	"bcc@example.com"	Blind carbon copy, comma-separated	Counts toward 50-recipient limit
Tag Optional	"confirm_email"	Single tag for categorization and statistics	Max 1000 chars
Metadata Optional	{"key": "value"}	Custom metadata key-value pairs	—
Headers Optional	[{"Name": "Message-ID", "Value": "<id@example.com>"}]	Custom headers	—
Tracking opens Optional	false	Enable open tracking	Boolean
Tracking links Optional	"None"	Link tracking: HtmlAndText, HtmlOnly, TextOnly, or None	—
MessageStream Optional	"outbound"	Message stream ID; defaults to default transactional stream	—

Example output

{
  "To": "recipient@example.com",
  "SubmittedAt": "2024-01-15T12:00:00Z",
  "MessageID": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "ErrorCode": 0
}

Documentation of API endpoint that powers action: Postmark – Send Email

Error handling

Error code and type	Reason
401 Unauthorized	Invalid or missing API Token.
422 Unprocessable Entity	Invalid payload (e.g. sender not verified, missing required field, invalid attachment).
429 Too Many Requests	Rate limit exceeded; retry with backoff.
500 Internal Server Error	Provider-side error; retry with backoff.

FAQs

Where do I get the API Token?

In the Postmark dashboard, open your Server → API Tokens. Create a token and paste it into WeWeb as the connection’s API Token.

Can I send to multiple recipients?

Yes. Put comma-separated addresses in To Email(s) (or use Cc/Bcc). The total number of recipients (To + Cc + Bcc) per message cannot exceed 50.

How do I add inline images?

Add an attachment with Content (Base64), ContentType, and ContentID. In your HTML, reference the image with cid:your-content-id so the ContentID value matches.