In Outlook in Office 2016, the recipient contact autofill has a new category called “other suggestions” that suggests people outside of contacts and recent recipients, which annoyingly includes adresses that were entered incorrectly. So if you send a message with a typo in the recipient field, that nonexistent typo email will be forever suggested in the autofill. Unlike the true Contacts entries, these suggestions can’t be deleted through normal means. This registry key will enable a hidden option to disable the “other suggestions” category entirely while keeping the contacts autosuggest feature active.
Key name: DisableAutoCompleteUpdate
Key type: DWORD