ISPs and other email services use various metrics to gauge your email reputation, including:
Bounce rate: High bounce rates may indicate that you are sending to invalid or outdated email addresses. Spam complaints: A high number of users marking your emails as spam can severely damage your reputation. Engagement metrics: High open and click-through rates can improve your reputation. Sending volume: Sudden spikes in sending volume can be red flags for ISPs. Blacklist status: If you’re listed on email blacklists, your reputation will suffer.