Nobody really uses Acrobat Reader on MS-DOS anymore. Adobe continues to take action against unpopular copies.

The software company Adobe, like many other manufacturers of proprietary software, is sometimes very vehement against illegal copies of its applications. This is apparently also independent of the age and the purpose of the specific application, which shows a quite unusual DMCA takedown request. Because Adobe has used this clause in US copyright law to block a tweet with a link to a 27-year-old version of Acrobat Reader 1.0 for MS-DOS.

The F-Secure security researcher Mikko Hyppönen writes on his Twitter account. First the magazine Torrentfreak reported about it. Strictly speaking, the specifically complained tweet is already more than five years old and, irritatingly, is still available.

In response to the DMCA request, it was not the original tweet from Twitter that was blocked, but a tweet in a bot account from Hyppönen that retweeted its five-year-old archive. In this bot account, the reference to the extremely old version of Acrobat Reader has now been interpreted as a copyright infringement.
Automatic DMCA requests with problems

The entire process seems very unusual even in the context of the numerous DMCA inquiries that repeatedly hit pages with user-generated content. There is also some evidence that the DMCA request was created by a fully automated system.

This assumption is supported not least by the fact that the actual hosting platform that distributes the old version of the Acrobat Reader does not seem to be affected by the DCMA request, but only the link to it from the Hyppönen bot account . The security researcher wants to leave his original tweet online, as Torrentfreak confirms.