To fix Apple Mail not receiving emails, start by checking your internet connection and make sure the mail server is working. Next, open Mail → Settings → Accounts and verify your IMAP/SMTP settings and password. Force-sync the mailbox, rebuild it if needed, and update macOS to avoid compatibility issues. Also check Mail rules and confirm your iCloud or mailbox storage isn’t full. If the problem keeps recurring, keeping a backup of your emails with the SysInfo iCloud Backup Tool helps protect your data during sync issues.