Enable ”Notify” will give user that have received a share link a notify e-mail when there is new content in the shared folder. “Notify” will not mail every time there is a new file, only on the first file or batch of files and then ones every hour, so you do not need to worry that your clients will be spammed with notify mails. You can modify share links to enable or disable “Notify” like other share options.
There is also a master option under the preferences menu to turn on/off “Notify“ on the account.
Remember you need to be administrator to do this.