A mailbox is a repository for email. It is used to store emails for one or more email addresses. When a user connects with a mail client application (Outlook Express, Eudora, etc.), they connect to a mailbox to retrieve their email. When creating a mailbox, MailEnable will automatically create an email address for each domain in the post office, using the format mailboxname@domain. A mailbox can have multiple email addresses. This means a user only requires one mailbox to connect to, from which they can retrieve email from all their email addresses.