TIdSMTP and punycode domains.

[SergJP]

My company got a Russian domain 'инвенто.рф'
MS Outlook sends  and receives emails without any problem and not use of punycode convertation.
But I need to make a software email reminder for personnel. 

   UnicodeString email = "slon@ивенто.рф";
   IdMessage->Recipients->EMailAddresses = email;
   if (IdSMTP->Connected())
       IdSMTP->Send(IdMessage);

got an exception: <slon@??????.??>: domain missing or malformed

wher I use a punycode conversion for this domain "slon@xn--b1aghucg1a.xn--p1ai", Indy sends this letter quietly, but letter nowere comes.
Encoding of headers I try both UTF-8 and KOI-8R. Same result.

Maybe any ideas?