title: UTC Time, Timezones, Daylight Savings, and Daylight Savings switchover dates
body: <p>I'm building an application which will be able to send emails at any specific local time to any place in the world. </p>
  
  <p>For example, my daily schedule (localtime):</p>
  
  <ul>
  <li>8:00 AM  - Send email to John in Toronto, Canada</li>
  <li>9:15 AM Western Standard Time (Australia) - Send email to Bob in Perth, Australia</li>
  <li>10:12 PM  - Send email to Anas in Rabat, Morocco</li>
  </ul>
  
  <p>I want to be able to execute this code on and Amazon EC2 server in a single location (e.g. São Paulo, Brasil). </p>
  
  <p>I also know that Toronto is in Eastern Standard Time, (UTC - 5h) , but from March 11, 2012 to November 4, 2012, it is in  Eastern Daylight Time (UTC - 4h).</p>
  
  <p>I also know that Perth is in Western Standard Time (UTC + 8h), with no daylight savings. </p>
  
  <p>I also know that Rabat is in Western European Time (UTC), but from April 29,2012 to July 20,2012,  and August 19,2012 to Sept 30, 2012 it is in in West European Summer Time (UTC + 1h)</p>
  
  <p>To keep track of these combinations of time zone, daylight savings, et cetera, I will, of course insist that all internal server times be in UTC. However, I need some way to keep track of when and how each time-zone jurisdiction switches time zones because of Daylight Savings or (in the case of Rabat) Ramadan, and then adjust my crontabs to accommodate these changes. </p>
  
  <p>Is there an authoritative web service or set of tables somewhere which would help me keep these timezone changes in sync with my desire to deliver emails at the same local time every day to users in different time zones with different switchover dates for daylight savings?</p>