Understanding IP reputation: how it works and how to monitor it

IP reputation is one of the biggest factors in email deliverability. Here is how it works.

What affects IP reputation

• Spam complaints: The #1 negative signal
• Bounce rate: High bounces indicate poor list hygiene
• Spam trap hits: Sending to known trap addresses
• Volume consistency: Sudden spikes are suspicious
• Engagement: Opens, clicks, and replies improve reputation

How to monitor

• Google Postmaster Tools (Gmail reputation)
• Microsoft SNDS (Outlook reputation)
• Sender Score by Validity
• Your ESP's deliverability dashboard

Recovery

If your IP reputation tanks, reduce volume to only your most engaged subscribers. Gradually increase over 2-4 weeks as reputation recovers. This is essentially a re-warming process.