This is more of a feature suggestion than an issue. I hope it will be considered.

As a administrator of a Joomla site, I would like the extension updates list to also show me a list of third-party extensions that do not have update notifications, so that I can be reminded to manually check their sites for new releases.

Steps to reproduce the issue

In Joomla admin panel, go to Extensions -> Manage -> Update. Or click the "View Updates" button on the control panel where it says "X Extension Update(s) are available"

Expected result

In addition to the current list of extensions that have update servers and are shown here if an update is available, I would also like to see a list of all the third-party extensions that do not have an update server.

Actual result

At the moment, only the extensions with update servers that have an update available are listed.

System information (as much as possible)

This applies to the latest Joomla release (3.6.4).

Additional comments

I am raising this ticket because one of my system owners has expressed frustration at not having any visibility about version updates for several of his extensions.

In an ideal world, of course, all extensions would provide update information to Joomla. But a lot of extensions do not, and in the absence of this, it would be really helpful if Joomla could provide a list of these extensions. This will at least give the site administrator a clear visual reminder at a regular interval of what needs to be checked.

This list doesn't have to be shown on the extension updates page, but it seems like a logical place to put it to me, as the administrator will be thinking explicitly about updates when he goes there, so it will be a timely reminder.

As things stand, it is very easy to neglect doing updates on these extensions. And even if you are keeping an eye on it, it's easy to simply to forget about one of them, which in turn opens up the possibility of security holes on one's site even though you think you're fully up-to-date.