> ## Documentation Index
> Fetch the complete documentation index at: https://www.plain.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# replyToThread

> Send a reply to the customer on a thread using the most appropriate channel automatically. Supports threads where the last inbound message is an email, a Slack message, or a form submission. If the thread has no messages yet, an email is sent to the customer. Requires the `thread:reply` (or channel-specific send) permission.