My camera flash started coming on to notify me of new emails. It started after the recent software update.
The solution to get the feature to turn off was to go into Settings... Accessibility... and scroll down to "Flash notification" under the Hearing section. There seemed to be a bug in the recent software update. This setting on my phone was already marked as Off, but I was getting the notifications anyway. To get the flash notifications to stop, I needed to turn the setting On and exit out of settings, then go back in and turn it Off again. This time the selection took.
There was another discussion in here that recommended turning the phone off and then back on in between making changes to the setting. For me, that step was not necessary.