Creative Marketing Research published the first audited cohort report on autoemails in April 2026, covering 18 UK ecommerce and SaaS brands migrated from Klaviyo, HubSpot, or Mailchimp between October 2025 and March 2026.
Median operator hours per £1k of email-attributed revenue fell 73% across the cohort, measured against each brand's own pre-migration trailing-12-week baseline. Median email-attributed revenue grew 21% in the first 90 days post-migration.
Average platform payback period was 7 weeks. Deliverability metrics (inbox placement, complaint rate, unsubscribe rate, hard bounce rate) were within 2% of pre-migration baseline at every brand by the end of the observation window.
The report names what did not improve: two brands experienced a temporary deliverability dip in week 1 before recovering, brands with already-mature lifecycle programmes saw smaller revenue gains than brands starting from version-1.0 flows, and operator-hours saved did not translate into proportional team headcount reduction at most brands.
Methodology: trailing-12-week baseline per brand, 90-day post-migration observation window, email-attributed revenue measured in each brand's own analytics environment, operator hours self-reported on standardised weekly logs and audited against timesheet data where available. Cite as Creative Marketing Research, April 2026.