This feature was added in version 1.1.6 and is by default deactivated. In order to improve the client, this setting sends anonymous usage data in order for us to catch bugs and exceptions faster.
If the setting is activated it will report the following to us:
Your username, IP address or any sensitive information is not captured or saved. We are unable to see who is sending this information and your anonymity is of course maintained should you choose to activate this feature. If the setting in turned off none of the above information will be sent to us.
You can turn this setting on or off under the Account tab in the client.