How does the Countdown Timer work in emails?

Countdown Timer is a GIF image that counts down to a specific date and time. It works as a PHP script which creates a looping GIF counting down to a time.

Every time when recipient opens an email, animated GIF loops for 90 seconds and then reset.

Countdown in emails are compatible across all platforms. However, some versions of Microsoft Outlook display first frame of animated GIF only. 

Client Displays Image Counts down
AOL YES YES
Gmail YES YES
Yahoo! YES YES
Outlook.com YES YES
Thunderbird YES YES
Outlook 02/03 YES YES
Outlook 07/10/13 YES NO
Outlook 2011 YES YES
Apple Mail YES YES
iPhone YES YES
Android YES YES