UFN_EXCHANGESERVERAPPUSER_UNIQUEEMAILADDRESS

            create function dbo.UFN_EXCHANGESERVERAPPUSER_UNIQUEEMAILADDRESS
            ( 
                @EMAILADDRESS dbo.UDT_EMAILADDRESS
            )
            returns bit
            with execute as caller
            as
            begin
                declare @VALID bit
                set @VALID = 1

                if (select count(ID) from dbo.EXCHANGESERVERAPPUSER where EXCHANGESERVERAPPUSER.EMAILADDRESS = @EMAILADDRESS and EXCHANGESERVERAPPUSER.IDENTIFIERTYPECODE <> 0) > 1 begin
                    set @VALID = 0
                end

                return @VALID
            end