A mailbox export is a bulk copy of email messages and often their attachments from an account. Depending on the system and export format, it may also include folders, timestamps, sender and recipient details, and other message metadata.
In a cyber incident, an exposed mailbox export can reveal sensitive conversations, business relationships, credentials or links, and documents shared as attachments. Attackers may steal mailbox data through compromised accounts or administrative access, then use it for extortion, fraud, or further intrusion. Defenders should restrict export permissions, monitor unusual bulk access, protect backups and exported files, and review affected mailboxes for sensitive data if an exposure is suspected.