Postmark helps deliver and track transactional emails for web applications. In a nutshell, the service replaces SMTP (or Sendmail) with a far more reliable, scalable and care-free environment.

To enable Postmark to send authenticated mail from your domain your SPF and DKIM settings must be enabled.

Table of Contents
  1. Postmark SPF Setup
  2. Postmark DKIM Setup
    1. Generate DKIM Key
    2. Publish DKIM Record
    3. Verify DKIM Signing

1. Postmark SPF Setup

Rather than utilizing an SPF record, Postmark requires a custom return path be setup. To do this, a CNAME record must be published that points to postmark.

How to set a custom Return-Path in Postmark?

1. Add a CNAME record to your DNS that points to

2. While logged into Postmark, choose Signatures.

3. Select the DNS Settings link on the domain you want to add the custom Return-Path domain on.

4. Navigate to the heading Set up a custom Return-Path and enter in your alias you used in your CNAME record you added to your DNS.

2. Postmark DKIM Setup

Postmark will always provide you with a custom DKIM signature. 

2.1 Generate DKIM Key

In your Postmark interface, follow the following steps:

  1. Navigate to your Sender Signatures tab.
  2. Under the domain you are adding DKIM authentication for, click DNS Settings or Add a DKIM DNS record.

  1. A DKIM record will be shown that needs to be added to your DNS as a TXT record.

2.2 Publish DKIM Key

1. Once the key is generated, you will need to load the key into the Sendmarc DKIM manager as a TXT record

This will resemble the below:

TypeHostTXT ValueTTL
TXT20180301173128pm._domainkeyPaste the key generated here1 hour (Default)

2.3 Enable DKIM Signing

1. Once the key is published, head back to Postmark and select Verify.