Question: I am working on a cron job which sends report to hundreds of users around the world. The cron should send an email to all my users at exactly 12am in the morning according to their timezone. Thanks in advance

Answer: 
```
Your Time | Timezone You Need
-----------------------------
12:00am     0
1:00am      -1
2:00am      -2
3:00am      -3
4:00am      -4
5:00am      -5
...
12:00pm     +/- 12
1:00pm      +11
2:00pm      +10
3:00pm      +9
...
------------------------------

```

You should be able to see the pattern start to develop here. The pattern should end up being something like Timezone Difference = (12-your current hour)
You need a list of which timezone all your users are in + whether they're using daylight savings or not.

For a complete list of timezones see this [wikipedia article](http://en.wikipedia.org/wiki/Time_zone)

Then every 15 minutes you need to have cron run a script to all the users in the current timezone offset. 

e.g. at UTC + 5:45 send your mails to all users in the "Kathmandu" timezone