Using your own domain to send review requests via email is good for your branding. You can avoid your emails being mistaken for spam by setting up DKIM and Return-Path. Unfortunately, this does not work for public domain email addresses (e.g. gmail.com, outlook.com).
When adding the email details to send review requests from your own domain, notice that you are prompted to verify DKIM.
DKIM (Domain Keys Identified Mail) is an email authentication technique that confirms that an email was indeed sent and authorized by the owner of that domain. Each email will have an encrypted DKIM signature.
We have instructions for generating DKIM and a custom Return-Path for Postmark.
How to Verify Your Email Address
STEP 1
From the Dashboard, click on Emails.
STEP 2
Click on Email Settings.
STEP 3
Add an email address and click Refresh.
STEP 4
Click on Verify.
STEP 5
Copy and paste the DKIM and the Return-Path code and click on Verify.
STEP 6
DKIM and Return-Path are now verified.