hi, i would suggest to implement a function since php currently has cron and smtp send.
I ask you to enter the possibility of making a reminder via email. The e-mail is created, it is decided when to send it (multiple dates perhaps in reference to a given event / chosen date) and the e-mail addresses are entered (addresses that do not have anything to do with the mailing list user address book).
The system thus sends emails to addresses without having to make groups, personal data etc.
I think it’s a great service for those with long-term deadlines.
thank you