Google offers a large array of solutions to migrate existing mail systems to its Google Apps solution. The offering is mainly organized around two tools, one for the Microsoft Exchange platform and another for Lotus Notes.

For the Microsoft Exchange platform, Google also provides a tool that users can install on their desktop. It can both upload existing data to Gmail and also ensure a thorough synchronization between Outlook and Gmail, meanwhile preserving the possibility for users to keep Outlook as their mail client.

The fact that Gmail uses the IMAP protocol, enables fetching messages from any standard mail server. In other, more complicated situations, specific developments using the Google API may be the only solution.