The scheme and the idea are very good. However, I will suggest improvement as:

1) make threshold parameter of the SP so you can change it on the agent job without altering SP

ALTER PROCEDURE dbo.usp_DBA_checkfordatabasefreespace

@threshold INT = 80

AS

2) it is comparing against the allocated space. In most databases, it is set as auto-grow. So the goal is really to alert on space remaining on the drive volume unless it is assuming the allocated database space is it.

CREATE TABLE #TMPFIXEDDRIVES (

DRIVE CHAR(1),

MBFREE INT)

INSERT INTO #TMPFIXEDDRIVES EXEC xp_FIXEDDRIVES

3) besides system database, you might want to consider online database only, not read-only, ....

FROM sys.databases

WHERE

name NOT IN ('master', 'model', 'msdb', 'tempdb', 'ADMINDB', 'Distribution') AND

name NOT LIKE '%ReportServer%' AND

DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND

DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'