Commons:Can I require notification of use of my files?
Contributors (or potential contributors) of Commons content sometimes want to be able to require notification of use of their files, at least for certain cases (eg commercial uses). Whilst requesting notification is possible, requiring notification is incompatible with Commons' licensing policy, which requires content to be available under a free license. This essay explains why such a requirement cannot be part of a free license.
Let's suppose that the user asking about requiring notification is named John Doe. None of the usual licenses have such a clause. You would have to write a custom license, say a new "John-Doe-attribution-notification-share-alike" license (JD-by-no-sa). You'll need to include in the license a section requiring that all subsequent commercial reusers of the work or of a derivative must notify John Doe at the address johndoe-at-some-e-mail or John Doe at some paper mail. Passing on the fact that that's a good way for Mr. Doe to receive lot of unrelated and unsolicited mail, you will need to make sure that the address remains very stable through the years, because if Mr. Doe is going to impose that contractual notification obligation, he better be serious about it and not force people to send useless notifications for decades to an address that he will abandon in six months from now.
As it is a custom license and not easily available, you'll also need to include a section providing that the full text of the JD-by-no-sa license must be included with every copy and with every derivative, or you'll need to establish and maintain a very stable website where you will guarantee that a copy of the full license will remain available. You'll need a section requiring that all copies and all derivatives must always be under the JD-by-no-sa license, and no other license.
You'll need to define an independently verifiable form of notification, because the reusers will want to be able to prove that they've complied with that contractual obligation, and not be at the mercy of Mr. Doe who may decide to sue them claiming that he did not receive it. The presence of the usual requirements of the usual licenses, like the attribution and other mentions, are objectively verifiable by anyone directly on the copies of the work, so there's no possible dispute on those points. But the notification is a different sort of requirement, it does not appear on the work, it would be a communication between the reuser and Mr. Doe and you need to make it verifiable. So, you'd have to provide that Mr. Doe must send receipts of the notifications (but if he doesn't, that makes the work non-free) or that the reusers must service the notifications by bailiff or send them through some form of certified mail.
You'll need to define what constitutes a distinct use requiring a notification. If different Wikipedia users decide at different times to use one or several of Mr. Doe's works, or derivatives of them, in several different articles, and if two hundred commercial websites mirror those Wikipedia articles, will the owners of each commercial website send a notification for each distinct use in each article? Logic says yes, but, if not, why not? Will each of them send a new notification each time a new cropped version is made and used? You'll probably have to consider also all other potential types of uses.
Really, Mr. Doe should make up his mind and take a clear decision: either he actually embraces the idea of offering his works under a free license and he agrees to a good old and usual free license, or he doesn't want to offer his works under a free license. Trying to accomodate people who are not sure if they want to offer a free license or not may be commendable, but it may be an impossible task.