SendLetter for ChatGPT

eu.sendletter/sendletter

Send real, printed letters by post across Europe. Requires a free account; quote before sending.

client:ChatGPT transport:streamable-http

Install SendLetter in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://sendletter.eu/api/mcp

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