Implement cron job validation

[pschlan]

To minimize abuse, cron job hosts should be validated by either sending a confirmation email to the domain owner or uploading a validation file.

[humble-barnacle001]

This might pose some issue as in suppose I wish to fetch a data from a API endpoint (using authentication) which is not owned by then it shall be a issue.

[humble-barnacle001]

But it can be such that there can be a limit above which there should be validation for example, if a job is run every hour, it need not be validated but below that must be validated

[pschlan]

That's true, and we should make sure we don't limit valid use cases.