Verify mail server connection programmatically in

问题:

I'm using custom SMTP servers and would like to verify the connection when user enters his own server credentials.

Exactly the same type of check as Adobe CF and Railo allow to do when adding mail server.

Sure, this does not guarantee that delivery will be working, but at least to check that entered server/username/pass are valid.

I can see one tricky way: try to send the email with cfmail and check the mail log. But I believe that it can be done with more elegant.

Is there any Java library available with standard ACF/Railo distro to help me? How would I use them? Examples are highly appreciated.

Thanks in advance.

EDIT:

Please don't be confused with Java tag present. Solution needed in CFML. Though it can use some Java libraries, if applicable.

回答1:

I think sfussenegger has the right idea. But instead of using a custom authenticator, what about authenticating via connect(..)? Only tested with gmail. But it seems to work.

EDIT: I tested this with CF9 & OBD successfully. Unfortunately, I had no luck with Railo ... bummer.

EDIT: Updated to add the missing "mail.smtp.auth" property. It should now work correctly with Railo as well.

    //Java Version
    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();
     }



<cfscript>
    //CF Version
    port = 587;
    host = "smtp.gmail.com";
    user = "[e-mail]";
    pwd = "email password";

    try {
        props = createObject("java", "java.util.Properties").init();
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.auth", "true");
        // or use getDefaultInstance instance if desired...
        mailSession = createObject("java", "javax.mail.Session").getInstance(props, javacast("null", ""));
        transport = mailSession.getTransport("smtp");
        transport.connect(host, port, user, pwd);
        transport.close();
        WriteOutput("success");
     } 
     //for authentication failures
     catch(javax.mail.AuthenticationFailedException e) {
           WriteOutput("Error: "& e.type &" ** "& e.message);
     }
     // for other failures
     catch(javax.mail.MessagingException e) {
           WriteOutput("Error: "& e.type &" ** "& e.message);
     }
</cfscript>

回答2:

Using Apache Commons Net, you can do something like this:

try {
     int reply;
     client.connect("mail.foobar.com");
     System.out.print(client.getReplyString());
     // After connection attempt, you should check the reply code to verify
     // success.
     reply = client.getReplyCode();
     if(!SMTPReply.isPositiveCompletion(reply)) {
       client.disconnect();
       System.err.println("SMTP server refused connection.");
       System.exit(1);
     }
     // Do useful stuff here.
     ...
   } catch(IOException e) {
     if(client.isConnected()) {
       try {
         client.disconnect();
       } catch(IOException f) {
         // do nothing
       }
     }
     System.err.println("Could not connect to server.");
     e.printStackTrace();
     System.exit(1);
   }

Where client is an instance of org.apache.commons.net.smtp.SMTPClient class. Code above was taken from the SMTPClient API Docs.

回答3:

That's not pretty, but could do: simply use try to send an email to an illegal address and see what error message you get. If the error message complains about failed authentication, you know what to do.

EDIT some working code:

here's some working code to validate Gmail credentials. Gmail doesn't complain about the illegal@localhost though. Now you could either try to search for a recipient that causes an exception or really send mail to an address and discard it immediately.. Edit: It's not even necessary to send something. Simply connect and handle a possible AuthenticationFailedException.

import java.util.Properties;
import javax.mail.AuthenticationFailedException;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;

public class Main {

    private static Session createSmtpSession(final String user, final String password) {
        final Properties props = new Properties();
        props.setProperty("mail.transport.protocol", "smtp");
        props.setProperty("mail.smtp.host", "smtp.gmail.com");
        props.setProperty("mail.smtp.auth", "true");
        props.setProperty("mail.smtp.port", "587");
        props.setProperty("mail.smtp.starttls.enable", "true");

        return Session.getDefaultInstance(props, new javax.mail.Authenticator() {

            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(user, password);
            }
        });
    }

    private static boolean validateCredentials(String user, String password) {
        try {
            Transport transport = createSmtpSession(user, password).getTransport();
            transport.connect();
            transport.close();
        } catch (AuthenticationFailedException e) {
            return false;
        } catch (MessagingException e) {
            throw new RuntimeException("validate failed", e);
        }
        return true;
    }

    public static void main(String[] args) {
        System.out.println(validateCredentials(args[0], args[1]));
    }

}