If Apple Mail is not receiving emails, it is usually due to an unstable internet connection, incorrect IMAP/server settings, outdated macOS, full iCloud mailbox storage, corrupted mailbox data, or Mail rules. Check connectivity, verify settings, rebuild the mailbox, and update macOS. To avoid data loss during such issues, keeping a backup using the SysInfo iCloud Backup Tool helps keep emails safe and accessible. Read more: https://www.sysinfotools.com/blog/apple-mail-not-receiving-emails/