IMSLP Forums

I have published on IMSLP some works of some Italian authors who died more than 50 years ago but less than 70 years ago published by Carrara.
After a couple of weeks, the publisher sent me a message saying that I need to remove every page concerning the works published by his house, claiming that they are under copyright. He did not mention anything else.
What should I do now? I replied inviting him to check out IMSLP rules.
Thanks a lot!

Update: I asked for the removal of all the pieces of this publisher I posted, since it claims that they are still under copyright (100 years from the date of the publications) and it has threatened legal actions against me.

Cross-post to the relevant discussion (because I was getting worried that this wasn't being addressed, even though it was)