# Overview * For the sending channels (email, SMS) that MultiMarket does not support, the white label can connect to the sending channel by itself and provide an external interface to connect with MultiMarket. The MultiMarket platform will call this interface according to the specifications of this document; * MultiMarket provides a set of interface docking APIs. White labels need to provide interfaces according to this specification. The API specifications are detailed below. * Then, on the white label management backend page (SMS account, email account page), select "Custom" when adding a new account, and configure the interface URL and public key (for authentication). --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.multimarkets.org/message-api/overview.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.