Microsoft Exchange Server 2003 entered the market on September 28, 2003 and continued the great messaging and collaboration experience that Microsoft Exchange Server had provided in previous releases. As we approach April 8, 2014, we want to inform users of Microsoft Exchange Server 2003 of the opportunities you have as we near the end of support for that version of Exchange.
We have been told by a variety of customers that some of the top concerns of businesses today involve data security, compliance, eDiscovery, mobile devices use / bring-your-own-device, and IT management. While Exchange 2003 was a leader in messaging space, its decade old capabilities may not meet the needs of a modern business. Exchange Online or Microsoft Exchange Server 2013 provide an updated, modern solution that address these top concerns and provide additional capabilities to meet your business needs. In comparing versions of Exchange Server, you will quickly see all of the benefits of moving to the current version of the platform.
Read more at source: http://blogs.technet.com/b/exchange/archive/2014/03/10/exchange-2003-migration-toolkit.aspx