UFN_EMAIL_ISACCOUNTVALID

      create function dbo.UFN_EMAIL_ISACCOUNTVALID(@EMAILADDRESS as nvarchar(255))
      returns bit
      with execute as owner
      as begin
          declare @ISVALID bit;

        if (select top 1 1 from dbo.EMAILINVALIDRECIPIENT where ADDRESS = @EMAILADDRESS and ISBLACKLISTED = 1) = 1
          set @ISVALID = 0;
        else
          set @ISVALID = 1;    

          return @ISVALID;
      end