Here is how to check the system drive space threshold in SQL Server. (You'll need to install SQL Mail first.)

1. Create the stored procedure (System_DriveSpace).
2. Execute the stored procedure as a job with parameters (Drive, Threshold, Global email address/individual email address).

1. Create the following stored procedure:

CREATE Procedure System_DriveSpace
 (
 @DriveLetter char(1),
 @Threshold integer = null,
 @EmailTo varchar(100) = null
 )
As
 set nocount on
 declare @FreeSpace integer
 declare @MinAllowed integer
 declare @EmailMsg varchar(200)
 declare @EmailSub varchar (200)
 declare @ServerName varchar(20)
 
 create table #tmp_DiskSize
  (drive varchar(2), 
  MB_free INT
 )
 insert into #tmp_DiskSize
 exec master..xp_fixeddrives

select @FreeSpace = MB_free from #tmp_DiskSize 
where drive = @DriveLetter
if @Threshold is not null
 select @MinAllowed = @Threshold
 else
 select @MinAllowed = 1024
 If @FreeSpace > @MinAllowed
 Select 'Plenty of space no need for alarm'  
 Else
  begin
   select @Servername=@@ServerName
   Select 'Drive ' + @DriveLetter + ' on ' + @ServerName + ' is below minimum threshold contact dba immediately'
   if @EmailTo is not null
    begin
     select @EmailMsg = 'Drive ' + @DriveLetter + ' is below minimum threshold on ' + @ServerName + '.  Only ' + cast(@FreeSpace as varchar) + 'Mb remaining.  Escalate to DBA and  Infrastructure team immediately'
     select @EmailSub =  '**** CRITICAL CONDITION on ' + @ServerName + ' ****'    
     EXEC master.dbo.xp_sendmail @recipients = @EmailTo,
      @subject = @EmailSub,
      @message = @EmailMsg
    end
  end
 drop table #tmp_DiskSize
 return 

2. Create the following job:

-------------------------
exec master..system_drivespace 'C', '512', 'sqlmonitors@abc.com'
exec master..system_drivespace 'D', '1024', 'sqlmonitors@abc.com'
exec master..system_drivespace 'E', '2048', 'sqlmonitors@abc.com'

Now, schedule the job accordingly.