A flash sale generates a lot of data. Most of it gets ignored because teams are immediately planning the next promotion. That's a mistake. A 60-minute post-sale debrief using the right metrics can double the ROI of your next campaign.
Open rate by send time — Compare your announcement email, mid-sale nudge and final-hours email. Final-hour sends almost always outperform on open rate; if yours didn't, your subject line or timing may need work.
Click-to-open rate (CTOR) — CTOR isolates email body performance from subject line performance. A high open rate with low CTOR means subscribers were interested but your offer or CTA didn't land.
Timer engagement — In Google Analytics, set up a UTM parameter on the CTA button in each email. Compare conversion rates by email send to see which message in your sequence generated buyers, not just clicks.
Revenue per email sent (RPE) — Total email revenue divided by total emails delivered. This is the single most comparable metric across campaigns of different list sizes.
Average order value during sale vs. baseline — Flash sales often attract bargain-hunters who buy at a lower AOV. Track this over several sales to understand whether your discounts are attracting your best customers or just your most price-sensitive ones.
New customer rate — What percentage of orders came from first-time buyers? High new customer rates are great for list growth but can drag down LTV if those buyers only buy on sale.
Sell-through rate — Did you clear the inventory you intended to? If a category significantly under-performed, investigate whether the discount was deep enough, the email targeting was right, or the timing was off.
Write a single-page debrief immediately after the sale while the data is fresh. Include: what worked, what didn't, one change to make next time. File it with the campaign assets. Future you will be grateful.