In some cases, you might need to rebuild a mailbox to update the list of messages in the mailbox. For example, if email messages appear to be missing or garbled, or if you can't find all relevant messages by searching.

To rebuild a selected mailbox, choose Mailbox > Rebuild.

For IMAP accounts, locally cached messages and attachments are discarded and the messages and attachments are downloaded again from the server to your hard disk. Your mailbox appears empty until the download is complete. This action is recommended for fast Internet connections only.