TIdIMAP4::RetrieveHeader speed

[Boba TC]

from my example above

Code:

  try{
    if( IdIMAP4->ExamineMailBox("INBOX",IdMlBx) ){
      UnicodeString s1,s2;
      //? s2=IdIMAP4->SendCmd("B29","FETCH 10:20 (FLAGS)",s1);//does not compile
      s2=IdIMAP4->SendCmd("B29 FETCH 10:20 (FLAGS)",s1);//compiles, but does not return and no Exception raised, why?
    }
  }catch  ....

what is the correct C++ syntax of TIdIMAP4::SendCmd method? can't find TIdImap4.hpp file on my 20 year old XP devbox