What’s the best order to check (authentication, engagement, content, domain)?

Systematic troubleshooting order:

1. Authentication: Check SPF, DKIM, DMARC alignment first. Easy to verify and fix. Foundational requirement.

2. Reputation: Review Postmaster Tools and SNDS. Understand your standing before investigating causes.

3. Engagement metrics: Analyze open, click, complaint rates. Identify if engagement degradation is the driver.

4. Content: Scan recent campaigns for spam triggers, new URLs, changed templates.

5. Domain history: Check for blocklisting, recent domain changes, or reputation events.

Start with technical, move to behavioral. Fix what is easiest first.

Check your papers before blaming the cargo or the crew.