To stop events firing in SharePoint 2007 we call a method to disable the event firing, perform our update and then call another method to enable it again. The code might look something like this.
this.DisableEventFiring(); item.UpdateOverwriteVersion(); this.EnableEventFiring();
This has changed in SharePoint 2010. We now have a protected property of type System.Boolean named EventFiringEnabled on the base class SPEventReceiverBase. Simply set this property to false to disable the event from firing before performing your update.
this.EventFiringEnabled = false; item.UpdateOverwriteVersion(); this.EventFiringEnabled = true;
The methods used in SharePoint 2007 are still in the 2010 API but are marked as obsolete. Take note!
MSDN – SPEventReceiverBase.DisableEventFiring Method
MSDN – SPEventReceiverBase.EnableEventFiring Method
MSDN - SPEventReceiverBase.EventFiringEnabled Property
Adrian Henke’s Blog – Disable SharePoint item events firing during item updates