Any pointers in the right direction would be much appreciated.
Toolkits, software, hints, warnings...

We are planning an email reminder system for our library.

It is planned to be in two main "chunks."

======= 1 =============================
Software that allows patrons to register for these reminders.
and to maintain the database.  Change the email, change the frequency
of the reminders etc.
Software than takes the registrations and sends a verification email out
for response before actually registering the patron.

======= 2 =============================
The second chunk is the actually email notification system

Two types of reminders:

1. these books are about to become overdue
2. the books we are holding for you to pick up are
about to be yanked from the hold shelf and returned to the general

The data is all in mysql tables, dumped from our ILS every night.

None of this is integrated with our overdues notification system (voice
robot, printed notices etc.)
  These are before the fact reminders only.

We have people who can manage perl, python, php...

TNRD Library System
Kamloops, BC, Canada