Log Message:
Update to 0.98. From the changelog:

- Added enhanced mail system status codes (RFC 1893/2034).

- Added support for rejecting all mail unless client is authenticated
  (either as a relay client or with SMTP authentication) if
  $REQUIRE_AUTH is set.

- Full domain names are now required in all addresses except for the
  null sender.

- Removed the "bounce must have a single recipient" rule, as it is
  currently causing more problems (with address checkers) than it is
  solving (spammers no longer use this technique).

- Fixed one-off bug in counting recipients for $MAXRCPTS.

- Truncate UIDL responses to 70 characters as per RFC 1939.

- Added QMQP and QMTP "reject" front ends, for completeness.

The enhanced mail system status codes together with the $REQUIRE_AUTH
change should make smtpfront compliant with RFC 2476's requirements for
a "message submission agent", suitable for use on TCP port 587.