问题内容: I want to build an stmp client using c++ for learning purposes. After I managed to implement the initial connection + auth login I am stuck on sending the message after using the data command. Here is my code void sendmail() { write_command("MAIL FROM: <foo@bar.de>"); write_command("RCPT TO: <bar.foo@baz.de>"); write_command("DATA"); write_command("Subject: testmail"); // HANGS here