title: error when using sendmailR to send email
body: <p>I want to use <code>sendmailR</code> send email via <code>smtp.exmail.qq.com</code> server,I looked at the sample to do it ,but failed,how can I work it out?</p>
  
  <pre><code>sendmail(
        from="***@companyName.com",
        to="***@companyName.com",
        body="Hallo",   
        subject="from R procedure",
        control=list(smtpServer="smtp.exmail.qq.com"),
      )
  
  Error in socketConnection(host = server, port = port, blocking = TRUE) : 
    cannot open the connection
  In addition: Warning message:
  In socketConnection(host = server, port = port, blocking = TRUE) :
    localhost:25 cannot be opened
  </code></pre>