Mailbox stores, which are also called mailbox databases, are where mailboxes are located. There are quite a few configuration settings for mailbox stores which are beyond the scope of this chapter, but going through the ESM GUI when manually creating a mailbox store should give you an idea of what can be configured.
Storage groups are used for physically breaking your databases up into smaller management groups. This is done for several reasons. Chief among them are so you have more numerous but smaller databases, a logical organization of mailboxes, or faster Exchange backups and restores. The Exchange Server can run one simultaneous backup for each storage group. So if you have 10 databases spread across two storage groups, you can have two backups running in parallel; if you have 10 databases spread across five storage groups, you can have five backups running in parallel.
Recipient policies are used for controlling how the RUS stamps mail-enabled objects. It is in charge of stamping objects with the correct email addresses as well as Mailbox Manager settings, such as automatically deleting and reporting on messages that exceed certain ages and sizes. Companies that have multiple divisions and want different email addresses for users in the different divisions use multiple recipient policies for configuring the email addresses. Each recipient policy has a filter that specifies the mailboxes it should configure with its rules.
Address lists are special groupings of email accounts that allow users to quickly find specific email users that are part of some logical grouping in the GAL. The RUS is responsible for creating and maintaining the address list links to the mail-enabled objects. The RUS links an address list to mail-enabled objects by adding the address list’s distinguished name to the object’s showInAddressBook multivalue attribute. Once an address list has been created, it can take hours or days for the RUS to fully populate the list by stamping all related objects’ showInAddressBook attributes, depending on the size of your organization.
Exchange Server 2003 has introduced a new type of distribution list: the query-based DL. These are, as implied by name, distribution lists that are built on the fly based on a query; specifically an LDAP query against Active Directory.