To quickly download your iCloud mailbox, use the iCloud Backup Software. It helps you save all emails to your computer or external storage in one go. You can export messages with attachments in formats such as PST, PDF, or EML. The software maintains folder hierarchy and ensures that metadata and formatting stay intact. It also supports selective backup using date filters to save time and storage space. With a few simple clicks, you can create a secure offline copy of your iCloud emails effortlessly.