Today I was looking through one my WordPress Sites and noticed a bunch of errors example:

domain.com/autodiscover/autodiscover.xml

This error is related to Microsoft clients doing autodiscover on your domain. This is used by Microsoft Outlook, Office 365, etc.

This can be resolved by adding this line in your .htaccess file in the root directory of your website:

Redirect 204 /autodiscover/autodiscover.xml

This type of response has much lower overhead than a 404, and the 204 response can be cached. The 404 error may not be cached at all times.