Checking mailbox sizes in Exchange 2007 involves determining the amount of storage space occupied by individual mailboxes on an Exchange server. This information is crucial for managing mailbox quotas, ensuring optimal server performance, and preventing mailbox storage issues.
Regularly monitoring mailbox sizes helps identify users who may be exceeding their allocated storage limits, potentially leading to email delivery failures and performance degradation. Additionally, it enables proactive management of mailbox growth, allowing administrators to adjust quotas or implement retention policies to prevent mailboxes from becoming excessively large.