MailInApp for ChatGPT

com.mailinapp/mcp

Build and send interactive email campaigns: studio editing, contacts, sending, results.

client:ChatGPT transport:streamable-http

Install MailInApp in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://mailinapp.com/api/mcp

Custom connectors are a paid-plan feature and take a remote URL only. ChatGPT cannot run a packaged server locally. ChatGPT docs