Well, it's software. Anything is possible. But users with access to the Customer Notes are not restricted to just editing their own notes. They can edit any of the notes on the customer file. Having a restriction like this usually means adding another option, because others find the rule too restrictive. For example, some people use specific UserId's for collection notes, so that they can be separately printed on the Overdue Receivables report.
Still, it's a reasonable suggestion. I think partly the security issue is dependent on what you are using Notes & Alerts for in your internal business process.
Thanks for the contribution.
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Andrew Bates