Do open rates still matter post-MPP?

Less Than Before. Open rates still provide some directional signal but MPP significantly degraded their reliability. Apple Mail users show inflated opens regardless of actual behavior.

Opens remain somewhat useful for non Apple segments if you can identify them. For overall strategy, prioritize click rates, conversions, and reply signals that require actual engagement.

Do not abandon opens entirely but weight them appropriately. They matter less and need supplementation with more reliable engagement indicators.