This is one of the options that is not part of the users options stream stored in
ACC_OPTIONS. This data is stored in a structure fashion, because other sessions need to know the settings of all other users when generating notifications.
When "Send the notifications by e-mail" is checked,
K_TABLE=-1 and the current users key.
select NOTIFY from ACC_RIGHTS where K_TABLE=-1 and K_USER=:K_USER