Email Program Migration and List Rebuild

The email program had been running on Mailchimp for four years, and on paper the list looked healthy: roughly 85,000 contacts and growing. The numbers told a different story. Open rates had fallen every single year as the list grew, not because the audience changed, but because unengaged and undeliverable contacts accumulated without ever being removed.

Mailchimp’s handling of hard bounces made the problem invisible. Addresses that bounced were suppressed from future sends but remained in the list count, keeping the reported bounce rate artificially low while the underlying list quality quietly deteriorated. By early 2026 the program was broadcasting to a dirty list with poor deliverability, unreliable segmentation, and no accurate picture of true engaged audience size.

Rather than migrate the full list, the decision was to start with the 35,000 cleanest, most engaged contacts and build back up deliberately. The goal was a deliverable foundation first, scale second.

The program launched on Constant Contact on March 13, 2026. The first send surfaced approximately 943 contacts Mailchimp had been quietly managing as soft bounces. By the second send, five days later, the bounce rate had dropped from 2.4% to 0.7% as the new platform validated addresses and began building a clean baseline.

From there, four audience segments were reintegrated in controlled batches through May. Each expansion temporarily spiked bounces as new addresses were validated. Rather than let those accumulate on the main list, four targeted re-engagement sends were deployed in late May to isolate and suppress bad contacts before they affected the primary program. By the end of May, 917 contacts had been suppressed across those sends.

By the end of May 2026 the list stood at approximately 100,000 clean, verified contacts, exceeding the old Mailchimp headcount on a deliverable basis. May was the first month with properly configured UTM parameters in place and the first clean year-over-year comparison available for the new platform.

Email revenue in May came in at $28,691, up 27% over May 2025 ($22,631). That result was achieved on a list still smaller than the old Mailchimp volume and far cleaner in composition. The program entered June with a larger and healthier list than it had before the migration, on a platform better suited to segmentation and compliance, with one month of clean data showing meaningful improvement in revenue per send.