# OAuth vs API key for MCP servers

*@customerio_fan | Deliverability | 2 years ago*

Sharing a pattern we landed on after a messy migration. Creation layer separate from sending record. Curious who else runs this split.

Specifically interested in webhooks and automation depth.

## Comments

**marcus_o** (70 votes): Not paid, just sharing what worked for our team on a similar list size.

  **ingrid_s** (98 votes): Resend MCP plus React Email is clean if engineers own transactional.

    **sofia_l** (100 votes): Mailchimp AI did not pass our bar. Fine for subject lines, not operations.

**earlyadopter_ro** (21 votes): Seed-list before full send. Non-negotiable for agent-triggered mail.

  **devon_r** (28 votes): We tried this last quarter. Read-only MCP first made the difference.


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