When you follow the basic setup instructions, email for recipients in your domain is delivered to their Gmail inboxes. This configuration, referred to as direct delivery, is appropriate for domains where all or most users will be using Gmail. However, your situation may call for a more advanced delivery option.

If your users currently have legacy mail accounts, on Microsoft Exchange for example, you can have mail delivered to their Gmail account, their legacy account, or both accounts.

• If some users use Gmail and others use their legacy accounts, you can have mail delivered to a Gmail account or a legacy mail account depending on the recipient. This option is called split delivery. (Learn how to configure split delivery.)


• If you want Gmail users to receive mail in their legacy accounts as well, you configure your domain for dual delivery. With dual delivery, users receive mail in two inboxes (both Gmail and the legacy email system), although each user typically reads his or her mail in only one of the inboxes. Dual delivery provides continuity in the legacy system during the evaluation of Gmail, which assists in troubleshooting problems or in rolling back if necessary. (Learn how to configure dual delivery.)


• If all mail needs to flow through your legacy mail server, for example if the mail server integrates with other corporate systems, you need to configure dual delivery.