my $file = "\"/home/.../msg-2575-4.html\"";
unlink($file)
is the equivalent of doing
rm "\"/home/.../msg-2575-4.html\""
Obviously, the correct shell command is
rm "/home/.../msg-2575-4.html"
so you want
my $file = "/home/.../msg-2575-4.html";
unlink($file)
or
my $file = '/home/.../msg-2575-4.html';
unlink($file)
If that second rm
command works, so does that Perl command.