4.4BSD/usr/src/usr.sbin/sendmail/src/KnownBugs

* Null bytes are not handled properly (changing this would require major
  internal changes -- for example, no C library support could be used to
  handle strings).

* There are cases where route-addrs do not get angle brackets around them,
  such as in the "-r" flag on mailers or in the From_ line created when
  mailing to files.