Outlook is retiring the "Contact Masking" feature on March 31, 2026, which allowed hiding suggested recipients. This affects Exchange Online users but not POP/IMAP or Exchange On-Premises accounts. Hidden contacts may reappear, with no replacement feature provided. No admin action is required.
Applies to: Microsoft 365 suite
Source: mc.merill.net — data via Merill Fernando's open archive (MIT).