Last month Microsoft announced that they enable auditing by default on every mailbox. Before this, you needed to run a script on every newly created mailbox to enable auditing for the items you wanted. Microsoft provided a script for this that can be found on GitHub.
The announcement can be found on techcommunity.
In this announcement, they say that every new mailbox gets the default set of auditing. This default set can be updated from Microsoft’s side, but when you have enabled auditing by yourself or the script, they provided it stays that way.
So now you can choose, keep running your script with your auditing settings or move over to the default set from Microsoft. Moving over is very simple. Go over every mailbox and set “DefaultAuditSet”. As options for “DefaultAuditSet” you have Owner, Admin and Delegate.
You can use the script below to set everything back to default.