Postmark

Postmark

ActiveCampaign's transactional email service. Known for raw speed and excellent inbox placement. Per-Server API tokens.

Easy~5 minAPI

Prerequisites

• A Postmark account. Free trial includes 100 emails on a sandbox server.
• A verified Sender Signature (single email or full domain).

Step-by-step

Verify your sender

Postmark dashboard → Sender Signatures → Add Sender Signature. Enter a single email (verify via clicking the link in the email Postmark sends), or set up Domain DKIM/Return-Path.

For production, use Domain DKIM — recipients see the email as truly coming from your domain.

Get the Server API Token

Postmark → pick a Server (or create one — separate Servers can have separate quotas/tokens) → API Tokens tab.

Copy the Server Token. Postmark uses the same token for both username and password fields.

Add the connection in SendGrail

WordPress admin → SendGrail → Connections → Add Connection → pick Postmark.

Fill in:

• Connection Name: Postmark
• From Email: your verified sender
• From Name: display name
• API Key: the Server Token from step 2

Click Save.

Test

SendGrail → Test Email → pick the Postmark connection → send.

Troubleshooting

422 Sender signature not found

Your From Email isn't verified in Postmark. Add it as a Sender Signature, OR verify the parent domain.

401 Unauthorized

Wrong Server Token. Double-check that you copied the Server Token, not the Account Token (which Postmark also shows).

Emails go through but aren't seen by recipient

Postmark separates Transactional and Broadcast streams. New servers default to Transactional — make sure your Server's stream type matches what you're sending. Marketing emails sent through a Transactional stream may be flagged.

What's next

• Failure Alerts — get pinged when Postmark rejects.
• Email Routing — route only transactional emails through Postmark while marketing goes elsewhere.