An updated Message Trace is now available from the Security and Compliance Portal on Office 365.
The Message Trace on Exchange Online is very well known tool to help troubleshooting mail flow issues but had few glitches.
With this new Message Trace, you will be able to create custom queries and save them, have a list of previous queries executed so you can reused them, increase to the last 10 days for real time analysis…
To start using this new Message Trace, connect to your Security and Compliance portal (https://protection.office.com) and go to Mail flow\Message trace section
From there you will find some default queries and any queries you will execute or save once you start using the new message trace
When you create a new query, the UI is a little bit simpler and more intuitive