You can send emails outside Apex and from scheduled jobs. All you need to do is to use wwv_flow_api.set_security_group_id; before apex_mail package as shown below:
begin
wwv_flow_api.set_security_group_id;
APEX_MAIL.SEND( p_to => 'to@youremail.com' , p_from => 'from@youremail.com' , p_subj => 'Subject here', p_body => 'Body here');
APEX_MAIL.PUSH_QUEUE;
end;
