使用java验证smtp服务器凭证而不实际发送邮件

Question

要验证smtp服务器凭证，我应该使用transport.connect()？

Session session = Session.getInstance(properties,authenticator); 

Transport tr=session.getTransport("smtp"); 

tr.connect(); 

检查smtp服务器证书是否正确？

Answer 1

这个问题：'Verify mail server connection programmatically in ColdFusion'有一个Java解决方案作为公认的答案的一部分：

int port = 587; 
String host = "smtp.gmail.com"; 
String user = "username@gmail.com"; 
String pwd = "email password"; 

try { 
    Properties props = new Properties(); 
    // required for gmail 
    props.put("mail.smtp.starttls.enable","true"); 
    props.put("mail.smtp.auth", "true"); 
    // or use getDefaultInstance instance if desired... 
    Session session = Session.getInstance(props, null); 
    Transport transport = session.getTransport("smtp"); 
    transport.connect(host, port, user, pwd); 
    transport.close(); 
    System.out.println("success"); 
} 
catch(AuthenticationFailedException e) { 
     System.out.println("AuthenticationFailedException - for authentication failures"); 
     e.printStackTrace(); 
} 
catch(MessagingException e) { 
     System.out.println("for other failures"); 
     e.printStackTrace(); 
} 

Answer 2

public boolean confirmSMTP(String host, String port, String username, String password, String auth, String enctype) { 
    boolean result = false; 
    try { 
     Properties props = new Properties(); 
     if (auth.equals(true)) { 
      props.setProperty("mail.smtp.auth", "true"); 
     } else { 
      props.setProperty("mail.smtp.auth", "false"); 
     } 
     if (enctype.endsWith("TLS")) { 
      props.setProperty("mail.smtp.starttls.enable", "true"); 
     } else if (enctype.endsWith("SSL")) { 
      props.setProperty("mail.smtp.startssl.enable", "true"); 
     } 
     Session session = Session.getInstance(props, null); 
     Transport transport = session.getTransport("smtp"); 
     int portint = Integer.parseInt(port); 
     transport.connect(host, portint, username, password); 
     transport.close(); 
     result = true; 

    } catch(AuthenticationFailedException e) { 
     Logging.addMsg(e.toString(), "SMTP: Authentication Failed", false, true); 

    } catch(MessagingException e) { 
     Logging.addMsg(e.toString(), "SMTP: Messaging Exception Occurred", false, true); 
    } catch (Exception e) { 
     Logging.addMsg(e.toString(), "SMTP: Unknown Exception", false, true); 
    } 

    return result; 
}