> ## 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.

# sendThreadDiscussionMessage

> Send a reply to an existing Slack or email discussion. The message is posted in the original channel
(as a Slack thread reply or email reply) and recorded in Plain. For Slack discussions you may optionally
provide slackBlocks, set unfurlLinks, or broadcast the reply into the parent channel via replyBroadcast
(replyBroadcast cannot be combined with attachmentIds). Prefer sendDiscussionMessage for new integrations.