private void UserSelected(User user)
        {
            var recipient = new Message.Recipient
            {
                EmailAddress = new EmailAddress
                {
                    Address = user.UserPrincipalName,
                    Name = user.DisplayName
                }
            };

            AddRecipient(recipient);
        }
        private void ContactSelected(Contact contact)
        {
            var recipient = new Message.Recipient
            {
                EmailAddress = contact.EmailAddresses[0]
            };

            AddRecipient(recipient);
        }