How to implement background tasks for notifications that will take into account time zones?

Question

JavaScript

Guys, tell me how to architecturally implement sending mail notifications through background tasks that will take into account user time zones? How to create tasks, per user or one task for all users?
Let's say I need to send a letter every week to all users at 9 am. Let's say I have 100 users. Do I need to do 100 tasks or one task? If one, then set the interval to an hour or what?

Answer 1

One task that generates a pool of notifications with a send timer and one for sending notifications exactly at the specified time