JavaMail Issue : Can't send command to SMTP host

Question

I\'m trying to do java mail and im getting an error \"Cant send command to SMTP host\". Any help would be appreciated. And any future problems\' solutions if possible. The e

Answer 1

The server requires STARTTLS. Here's what I get if I do a manual SMTP session with telnet:

220 BLU0-SMTP122.phx.gbl Microsoft ESMTP MAIL Service, Version: 6.0.3790.4675 ready at  Mon, 18 Jul 2011 17:08:14 -0700
HELO jhmg.net
250 BLU0-SMTP122.phx.gbl Hello [70.123.155.64]
MAIL FROM:<zzz@zzz.com>
530 5.7.0 Must issue a STARTTLS command first

This server does not accept unencrypted connections

Answer 2

Today I gone through this same issue. But for me the issue is, in smtp server TLS was not enabled. So I have changed the mail properties like this.
mail.smtp.starttls.enable=false

Now every thing is working good for me.

Answer 3

Try adding from address

mail.setFromAddress("Name ");

Answer 4

In my case, I was able to find the root problem after I enabled mailer debugging.

Different ways to enable mailer debugging:

java -Dmail.debug=true ...

props.put("mail.smtp.starttls.enable", "true");
props.put("mail.debug", "true");

Jenkins config (/etc/default/jenkins):

JAVA_ARGS="-Dmail.smtp.starttls.enable=true -Dmail.debug=true"

More info: http://www.oracle.com/technetwork/java/faq-135477.html

My particular error was that I had an incorrect address in the "from:" line when the email was created. Google "G Suite" (google apps for business) requires the from-address to be in the same domain as the account owner. Eg. mycompanyname.com

The mailer debug revealed:

MAIL FROM:<jenkins-pipeline@bogusdomain.com> 550-5.7.1 Invalid credentials for relay [192.168.42.42]. The IP address you've 550-5.7.1 registered in your G Suite SMTP Relay service doesn't match domain of 550-5.7.1 the account this email is being sent from. If you are trying to relay 550-5.7.1 mail from a domain that isn't registered under your G Suite account

Answer 5

You need to set ssl trust to smtp.gmail.com

properties.put("mail.smtp.ssl.trust", "smtp.gmail.com");

and Authenticator as a parameter for session

        Session session = Session.getDefaultInstance(properties,new javax.mail.Authenticator(){
            protected PasswordAuthentication getPasswordAuthentication() {

                return new PasswordAuthentication(
                        sender, senderPassword);// Specify the Username and the PassWord
            }
        });