Monitor Reputation with Postmaster Tools

Gmail and Outlook/Hotmail each offer a free window into how they see your domain.

Google Postmaster Tools

Spam complaint rates, domain/IP reputation, authentication success, delivery errors for Gmail addresses.

Setup: sign in at postmaster.google.com, add your domain, confirm with the DNS TXT record, wait for data (needs meaningful Gmail volume), then connect in Settings > Email Services > Postmaster Tools.

Microsoft SNDS (Smart Network Data Services)

Filter results, spam complaints, trap hits, blocked status for your sending IP.

Setup: Settings > Email Services > Postmaster Tools > Microsoft SNDS (available on a dedicated IP), select your IP, download a CSV for deeper reporting.

Why check regularly

Catch a rising complaint rate or bad sending day before it snowballs. A weekly check of both is enough.