There will be times that you need to dismount a mailbox store on the fly. This could be for integrity checking, mailbox restorations, or to make email unavailable to some users for some reason. When you dismount a mailbox store, users with mailboxes in that store will be unable to retrieve their mail; users with mailboxes in other mailbox stores will be unaffected.
Exchange is very dependent upon Active Directory domain controllers. The list of domain controllers currently being used by a server is usually one of the first pieces of information you should gather when you encounter an Exchange issue. While this can be done through the GUI, it is much easier to get the data through a script.
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.