The real checklist for migrating email providers without a deliverability dip

This is the general version of the provider-specific migration guides (Resend, SendGrid, Postmark, Mailgun, Mandrill), pulling the steps that are true regardless of which provider you're leaving. Read the provider-specific guide for the exact field mapping, use this for the sequence.

Before you write any code

• Confirm your current provider's exact request shape and any provider-specific features you actually use (templates, tagging, batch sending) so you know what needs a manual equivalent versus what's a straightforward field rename
• Add Envello's SPF include and DKIM records alongside your existing provider's records, don't remove anything yet
• Verify your sending domain in Envello and confirm DNS has propagated

Code changes

• Swap the sending client and API key behind a flag or environment variable that lets you route a percentage of traffic to either provider
• Update error handling for the new provider's error codes, don't assume they match your old provider's
• If you used server-side dynamic templates with loops or conditionals, render that logic in your own application code instead, Envello's template system does variable substitution only

Rollout

• Start at a small percentage of traffic, watch delivery status and bounce rate in log search for at least a day
• Widen gradually, not all at once, over days rather than hours
• Only remove your old provider's DNS records and API integration once you've held at 100% with no issues for a few days

The one step people skip

Actually watching log search during the rollout window. A staged migration only catches problems early if someone is looking. Set a calendar reminder to check delivery status at each stage rather than assuming silence means success.