Best of the inbox: migrating ESPs without losing deliverability

Best of the inbox: migrating ESPs without losing deliverability
Switching providers is where reputations go to die. These checklists keep your inbox rate intact.

📋 Before
— Don't move reputation, rebuild it — new ESP = new IPs. Plan a 2-3 week warm-up on the new platform before cutting volume over.
— Export with engagement data — bring open/click history so you can seed the new IPs with your best contacts first.

🔀 During
— Run dual-send overlap — keep the old ESP live for transactional mail while you ramp the new one. No hard cutover.
— Re-publish SPF/DKIM for the new sender — and verify alignment before the first real campaign.

✅ After
— Monitor seed placement daily for 30 days — catch reputation dips while they're still fixable.

Why these made the cut: the overlap period is the trick nobody mentions until it's too late.

Saved you ~2 hours of vendor docs and dread.