alekseiharlasov May 27, 2019 at 10:42 PMI got a reply from Microsoft Technical Support which actually works, however, Microsoft said that this is up to you to software developers to properly integrate with Outlook and prevent the security prompts from happening.Correct Values for Office 2016 ProPlus ClickToRun (O365)This results in the following Registry keys being set:Key: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\<version>\Outlook\SecurityValue name: AdminSecurityModeValue type: REG_DWORDValue: 3Key: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\<version>\Outlook\SecurityValue name: PromptOOMSendValue name: PromptOOMAddressBookAccessValue name: PromptOOMAddressInformationAccessValue name: PromptOOMMeetingTaskRequestResponseValue name: PromptOOMSaveAsValue name: PromptOOMFormulaAccessValue name: PromptSimpleMAPISendValue name: PromptSimpleMAPINameResolveValue name: PromptSimpleMAPIOpenMessageValue type: REG_DWORDValue: 2