Do you mean that the message was not sent successfully?
Could you provide a screenshot or error message?
Here are some possible solutions to address the problem what the message are not sent successfully:
- Check if your network is working.
- If you’re using the Teams desktop or mobile app, try using the web version: https://teams.microsoft.com/.
- Temporarily disable your firewall/antivirus > login to the desktop app and check again.
- Uninstall Teams from your device, then reinstall it.
- Clear the Teams cache from your device.
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