* Do not scramble innards when a query on the output queue is cancelled.
* Do not close tcp socket twice.
* Mailboxes containing spaces in their names are quoted.
+ * Give ESRCH, not EAGAIN, if _check called with no queries outstanding.
* adns_rr_hostaddr naddrs is -1 on temporary failure (as documented).
* Reject TXT RRs with no strings.
* Correct error messages for qname CNAME foo, foo CNAME bar.