Google Postmaster Tools is a free dashboard showing how Gmail sees your domain: spam rate, domain and IP reputation, authentication pass rates, encryption, and delivery errors, for senders with meaningful volume.
Why is Postmaster Tools empty?
Volume is too low for Gmail to report, the domain is not verified, or you are looking at the wrong domain (From versus DKIM d=).
Why does Google Postmaster Tools matter for deliverability?
It is the only direct view into Gmail's opinion of your mail, and Gmail is usually the largest share of any consumer list.
What is the first step to get started with Google Postmaster Tools?
Add your sending domain and verify with a TXT record.
What is the most common Google Postmaster Tools mistake?
Verifying the root domain but sending from an unverified subdomain.