This doesn’t work:
$ svn add firstname.lastname@example.org svn: warning: 'icon' not found
$ svn add email@example.com@ A (bin) firstname.lastname@example.org
You must append another at-sign (“@”) to any filename that contains one that isn’t intended to be interpreted as a revision specifier.
I suspect this has been a first-time issue for a lot of Subversion users this week.