This custom alert will tell you when a database job is stopped. The query checks the job's enabled flag and if it's 0, an alert will be triggered based on the thresholds.
Note: To filter the results, i.e. ignore a specific job, add a "WHERE name NOT IN ('<list of jobs to exclude>')" clause to the query.
To create this alert, click into Alert and create a Custom Multiple Numeric SQL Alert and configure it similarly to this:
