There are a few steps you can take to diagnose message size issues on an NNTP server:
1. Check your server logs: Look for any errors related to message size or incoming posts.
1. Test message size limits: Send a few test messages with varying sizes to the server and see if any get rejected or cause issues.
1. Check server settings: Review your NNTP server configuration to confirm the maximum message size limit.
1. Monitor network traffic: Use a network monitoring tool to track network traffic and identify any potential bottlenecks that may be causing message size issues.
1. Check client software: Confirm that the clients posting messages to the server are not exceeding the maximum message size limit imposed by the server.
1. Contact support: If you’re still experiencing issues, contact your NNTP server support team for further assistance.