Validating smtp server credentials using java without actually sending mail

Question

To check smtp server credentials should I use transport.connect() ?

 Session session = Session.getInstance(properties,authenticator); Transport tr=session.getTransport("smtp"); tr.connect(); 

Is the smtp server credential verification method correct?

Answer 1

This question: “Test connection of the mail server programmatically in ColdFusion” has a Java solution as part of the accepted answer:

 int port = 587; String host = "smtp.gmail.com"; String user = " [e-mail] "; 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; }