Aug 22, 2019 12:20 AM|PatriceSc|LINK
It seems you are trying to invite a user whose account is (or should be) under your control (for example created directly in your Azure AD or kept in sync from an on premise directory owned by your organization or maybe a non existing account whose
mail ends with your own on premise domain name etc...). Use https://portal.azure.com/#blade/Microsoft_AAD_IAM/UsersManagementMenuBlade/AllUsers and see
if you find the user you are trying to invite.
It's not an invitation to an "event". This to invite external users to register themselves inside your own Azure AD tenant so that they can access your own resources using an account which is not under your control. It creates immediately a "guest" account
(to which you can immediately assign permissions etc...) which will be enabled once the user completed the registration process. Depending on the situation the user will be able then to just use his existing company or Microsoft account (or at worst will
have to create a new Microsoft account).