Administrators Send CRON mails in more human hours
 

Send birthday mails at 10:00 o clock of the birthday. Send weekly reminders on 8:00 or 10:00 on monday. It feels far better to receive a birthday email at 10:00 - or 10:57 - than checking on birthday an email that came from 0:00 and looks artificial made. It's easy to change that in scheduled tasks.

Let the emails get to the user when he will most take care of them.