remail: Fix the from mangling

The comment in mangle_from() says that if there is not a real name then the
email address is mangled by replacing @ with _at_. The comment is great
just the implementation is not doing so.

Add the replacement functionality.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

remail/maillist.py

@@ -233,6 +233,7 @@ class maillist(object):
         If $ORIGINAL_FROM does not contain a name, mangle the email
         address by replacing @ with _at_
         '''
+        mfrom = mfrom.replace('@','_at_')
         return '%s for %s <%s>' % (self.config.name, mfrom,
                                    self.config.listaddrs.post)