As I've already written, SourceForge.Net has limited things which you can do on git/mercurial servers and one of the things they have prohibited is sending emails.
This is one of few things which almost every projects uses so it has brought quite obvious reaction, people are reporting bugs that it stopped to working. The major reason for reporting bug is that this change was not at all communicated to users (nor users nor project admins), so it was just a surprise and every body expects bug and not this kind of reply.
As I don't have way to reopen the ticket, I had to open another one, that the documentation is wrong and I hope the reply will be slightly better.
SF.net, if you still don't believe people used this feature quite a lot, just look at number of bug reports you have in your tracker right now...