Error 0x800CCC0F in Outlook 2016 usually occurs due to a sudden loss of connection with the mail server. This can be caused by unstable internet connectivity, antivirus interference, incorrect email settings, or corruption in the Outlook PST file. To fix this issue, first check your internet connection and temporarily disable your firewall or antivirus software. Next, verify incoming and outgoing server settings and ensure the correct port numbers are used. If the error persists, the problem may lie in a corrupted or oversized PST file. Microsoft’s built-in ScanPST.exe sometimes fails to resolve severe corruption. In such cases, using a reliable third-party solution Aryson Outlook PST Repair Tool can help. It repairs damaged PST files, recovers emails, contacts, calendars, and other mailbox items, and works without Outlook installation. Repairing the PST file often resolves Error 0x800CCC0F and restores smooth email sending and receiving in Outlook 2016.