All programs for working with email outwardly resemble each other, they contain a tree structure of folders, each folder belong mails, a mail containing the 'From:', 'To:', 'Subject:', the text of the mail and attached files - is that the saw user. For every programmer email program, a 'black box' with complex and hard to understood structures, interfaces, formats, the rules of access and so on. Mailbox SDK is a universal tool to work with the various email programs using the Mailbox SDK API functions. You use a simple 5 Mailbox SDK API functions, and your program is compatible with more than 15 versions of the most popular programs: MS Outlook, MS Outlook Express, Thunderbird and Eudora. You did not change in the code of your program, if instead of MS Outlook Express decided to use MS Outlook. Mailbox SDK provides ready, workable examples of the most popular decisions, you simply take out these examples from Mailbox SDK and make owned software products: Backup Email, Email Extractor, Mailbox Viewer, Attach Extractor, and so on. The works to empower Mailbox SDK unabated, added new email programs and their release. In doing so, we support Mailbox SDK interface, which is why, if your application is already done, you simply update the version Mailbox SDK and get new opportunities for your product without changing its code.