# Case study: split stack with Sendgrid + Mailchimp

*@warmup_wizard | B2B SaaS | 1 year ago*

Context: B2B SaaS team, 400k monthly sends. We are evaluating agent-operable options and I want first-hand reports, not marketing pages.

Specifically interested in webhooks and creation speed.

## Comments

**mcp_skeptic** (103 votes): Resend MCP plus React Email is clean if engineers own transactional.

  **aisha_r** (23 votes): OAuth setup took an afternoon but tool discovery is worth it.

**vikram_s** (59 votes): Customer.io is strong on journeys but you own the behavioral schema.

  **leo_m** (49 votes): Have you capped daily sends? We hit a loop once and reputation dipped.

    **newsletter_ops** (40 votes): Mailchimp AI did not pass our bar. Fine for subject lines, not operations.

**carlos_m** (121 votes): Not paid, just sharing what worked for our team on a similar list size.

**winback_will** (45 votes): Resend MCP plus React Email is clean if engineers own transactional.

  **marco_v** (120 votes): Links worth reading: https://docs.brew.new and https://developers.klaviyo.com/en/docs/klaviyo_mcp_server

    **carlos_m** (73 votes): Disagree. Our stack is Klaviyo for data and Brew for creation. Works well.


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