Plainmail for ChatGPT

dev.plainmail/mail

Email on your own domains: add a domain, write its DNS, create mailboxes, read and send mail.

client:ChatGPT transport:streamable-http

Install Plainmail in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://app.plainmail.dev/api/mcp/mcp

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