New Outlook for Windows will support LDAP directories for S/MIME certificate lookup, enabling secure encrypted email with external partners. Rollout begins late May 2026 worldwide, mid-June in GCC. Admins configure LDAP via Exchange Online PowerShell; users add directories in Outlook settings. LDAP must not require authentication.
Applies to: Exchange Online
Source: mc.merill.net — data via Merill Fernando's open archive (MIT).