I know it's been a while since the last post in this topic, but to save duplicating I'll reply here. I think this is an absolute must have feature for the next major release of phpScheduleIt. We're currently running version 1.2.11 to loan out photographic equipment and laptops.
It's working great, but unfortunately it would seem we have forgetful users who don't return items on time, so more often than not when someone asks for an item they've reserved, we find ourselves chasing down the last borrower for 15 minutes to ask them to return the equipment. It would be great to have a configurable option for each resource where you could enable, shall we call them "return reminder" emails which fired off an email to remind the borrower that the item is due back soon.
Some thought would need to be put in to just when these emails were sent, e.g. if someone reserved an item for 4 weeks, you might want to set the email to be sent 1 day before it's due back, but if the item has only been loaned for a few hours, you might want the reminder to be sent when there's only 15 minutes of the reservation remaining, so this may need to be configurable. Also, it's probably a bad idea to give users the ability to turn this feature off in their communication preferences as it would defeat the point.
It would be good if the message was configurable by the administrator rather than hard coded
I hope this makes it into version 2. Great work!... looking forward to the next release