title: MIMEText UTF-8 encode problems when sending email
body: <p>Here is a part of my code which sends an email:</p>
  
  <pre><code>servidor = smtplib.SMTP()
  servidor.connect(HOST, PORT)
  servidor.login(user, usenha)
  assunto = str(self.lineEdit.text())
  para = str(globe_email)             
  texto = self.textEdit.toPlainText()
  textos = str(texto)
  corpo = MIMEText(textos.encode('utf-8'), _charset='utf-8')
  corpo['From'] = user
  corpo['To'] = para
  corpo['Subject'] = assunto
  servidor.sendmail(user, [para], corpo.as_string())
  </code></pre>
  
  <p>Everything is ok except the part of the Subject.
  When I try to send a string with special characters (e.g. "ação") it raises this error:</p>
  
  <pre><code>UnicodeEncodeError: 'ascii' codec can't encode characters in position 1-2: ordinal not in range(128)
  </code></pre>
  
  <p>How can I send emails with special characters in the Subject of MIMEText?</p>