Hook

tkt_sei_notify_on_role_visit

You can use the filter tkt_sei_notify_on_role_visit in order to customize the “Visitor” Role that should trigger the email sent by TukuToi Send Email If Plugin.

In other words, this allows you to determine what User Roles will actually trigger the emails, when an user of such role visits a post which is observed.

The filter expects an array of valid User Roles.
Pass 0 (int) if you want guests to trigger emails.
Empty array (default) triggers no email at all.

Example:

add_filter('tkt_sei_notify_on_role_visit', 'my_custom_notify_on_role_visit');
function my_custom_notify_on_role_visit(){
  $role = array( 'administrator', 0, 'subscriber' );// it sends the email if a user with role administrator, or subscriber, or even a guest is visiting. 
  return $role;
 }