Channel Metric Reference Email | Metric | How It Is Calculated | Typical Range | Insight Provided | |--------|---------------------|---------------|-----------------| | Delivery rate | Delivered / Sent | 95-99% | Sender reputation and list hygiene | | Open rate | Unique opens / Delivered | 15-30% | Subject line and sender name effectiveness | | Click-through rate (CTR) | Unique clicks / Delivered | 2-5% | Relevance of content and CTA | | Click-to-open rate (CTOR) | Unique clicks / Unique opens | 10-20% | In-email content quality among openers | | Unsubscribe rate | Unsubscribes / Delivered |…