TODO

   1
   2 Spec documents:
   3 RFC6530 Overview and Framework for Internationalized Email
   4 RFC5890 Internationalized Domain Names for Applications (IDNA):
   5                 Definitions and Document Framework
   6 RFC6533 Internationalized Delivery Status and Disposition Notifications
   7
   8 - rcpt verification for an internationalized message should require the
   9 destination supports the SMTPUTF8 extension
  10
  11 - transport ditto; nonsupport equates to perm-rej an triggers a bounce
  12
  13 - DSN support extended per rfc 6533
  14
  15 ======================
  16
  17 to-Alabel convert of helo name
  18 - smtp transport
  19
  20 ++ An "international" flag on the message?
  21 ++ An is-international expansion condition?
  22
  23 ++ helo-time option handling
  24 ++ conversion of utf-8 domains for DNS  rfc5890
  25 -- MSA mode: convert on forward?
  26
  27 dsn handling                            rfc6533
  28 logging
  29 - international msg
  30 - presentation of local-part in log
  31 -- a log option?
  32 encoding of local_part
  33
  34 Recieved-by header tracking info
  35 - WITH protocol types get UTF8 prefix
  36 - use for logging also
  37
  38 forwarding checks                       rfc6530 7.1 -3-
  39 - rcpt-time rejects get 533 mailbox name not allowed
  40 - mail-time rejects get 550 mailbox unavailable
  41 - bounces (see dsn handling)
  42
  43
  44 ++ expansions for to- and from-Alabel ? bug1567
  45
  46 enhanced status codes?                  rfc5248++
  47
  48 VRFY
  49 EXPN
  50
  51 non-smtp input