Preventing 'slide-out' of notification center?

On OSX 10.11, the Notification Center 'slides out' when I swipe left with two fingers on my trackpad. Normally, that would be fine, but it's also the same gesture that OS X Mail now uses to delete mail. So, when I swipe left to delete mail, I sometimes slide out the notification center instead.

It happens enough to be annoying, so I'd like to turn off the gesture for the Notification Center--I'll open it using the menu bar icon only. Can that be done? Thanks for your help.