Hey @lifan
Jacques here from Intercom Support. I hope all is well today!
How do you create this message? Do you type it in the composer in your Inbox and send it, or is it created via our API / Webhooks?
If created via API or Webhook the issue could be due to stripping out newline characters. We may need to dig deeper into this by getting a conversation URL.
Would you be able to reach out to our support team via the messenger and provide the Conversation URL so we can dig deeper into things?
Thanks! :)