API How To...
How To: Set Custom Email Properties
How To: Prevent Tracking of an Email
The EmailTrackingRecipientMailboxesUpdating event is a “pre” event which means you can prevent any further email tracking processing on the email by setting the Continue property of the context object to false. This will result in the sender and recipient mailboxes not being updated for the email.
How To: Change the Open SharePoint Location URL
By default, a property called SharePointLocationURL is set on tracked emails to indicate the parent location of where the file is saved in SharePoint (e.g. the List, Library, Document Set or Folder). This value supports read/write by the plugin and so you can modify the URL if you would rather the Open SharePoint Location action went to a different location than the immediate containing folder of the file (e.g. you might like to link to the Site instead).