Error 12221 on Windows when accessing webmail

Symptoms

Windows webmail returns 12221.

Likely cause

DoD certificates are missing or corrupt.

Fix

1. Install the latest DoD certificates from militarycac.com/dodcerts.htm. 2. If still broken, delete every DoD cert via IE > Tools > Internet Options > Content > Certificates > Intermediate Certification Authorities > select and Remove. 3. Reinstall via InstallRoot.

Sourced from militarycac.com. Rewritten for clarity.

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