My mail server request STARTTLS PLAIN

I changed to a new SMTP mail server which using port 587 submission with STARTTLS PLAIN authentication. How can I config this plugin to match the requirement?

When the test mail fail, I looked our mail server and see:
Dec 1 14:02:44 mail postfix/submission/smtpd[11094]: warning: gateway[10.11.22.1]: SASL CRAM-MD5 authentication failed: PDM2NTY2NjUyNDE3MDY1NzcuMTUxMjE2NTc2MkBtYWlsLm14ZG92ZS5jb20+

Here is the output for the failed test:

=============================
Test Message Sent
The result was:
bool(false)
The full debugging output is shown below:
PHPMailer Object
(
    [Version] => 5.2.22
    [Priority] => 
    [CharSet] => UTF-8
    [ContentType] => text/plain
    [Encoding] => 7bit
    [ErrorInfo] => SMTP Error: Could not authenticate.
    [From] => [email protected]
    [FromName] => 833
    [Sender] => [email protected]
    [ReturnPath] => 
    [Subject] => WP Mail SMTP: Test mail to [email protected]
    [Body] => This is a test email generated by the WP Mail SMTP WordPress plugin.
    [AltBody] => 
    [Ical] => 
    [MIMEBody:protected] => This is a test email generated by the WP Mail SMTP WordPress plugin.

    [MIMEHeader:protected] => Date: Fri, 1 Dec 2017 22:02:48 +0000
To: [email protected]
From: =?UTF-8?B?ODMz5bCP56uZ?= <[email protected]>
Subject: WP Mail SMTP: Test mail to [email protected]
Message-ID: 
X-Mailer: PHPMailer 5.2.22 (https://github.com/PHPMailer/PHPMailer)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8

    [mailHeader:protected] => 
    [WordWrap] => 0
    [Mailer] => smtp
    [Sendmail] => /usr/sbin/sendmail
    [UseSendmailOptions] => 1
    [PluginDir] => 
    [ConfirmReadingTo] => 
    [Hostname] => 
    [MessageID] => 
    [MessageDate] => Fri, 1 Dec 2017 22:02:48 +0000
    [Host] => mail.mxdove.com
    [Port] => 587
    [Helo] => 
    [SMTPSecure] => tls
    [SMTPAutoTLS] => 1
    [SMTPAuth] => 1
    [SMTPOptions] => Array
        (
        )

    [Username] => [email protected]
    [Password] => BJSDefz833
    [AuthType] => 
    [Realm] => 
    [Workstation] => 
    [Timeout] => 300
    [SMTPDebug] => 0
    [Debugoutput] => echo
    [SMTPKeepAlive] => 
    [SingleTo] => 
    [SingleToArray] => Array
        (
        )

    [do_verp] => 
    [AllowEmpty] => 
    [LE] => 

    [DKIM_selector] => 
    [DKIM_identity] => 
    [DKIM_passphrase] => 
    [DKIM_domain] => 
    [DKIM_private] => 
    [DKIM_private_string] => 
    [action_function] => 
    [XMailer] => 
    [smtp:protected] => SMTP Object
        (
            [Version] => 5.2.22
            [SMTP_PORT] => 25
            [CRLF] => 

            [do_debug] => 0
            [Debugoutput] => echo
            [do_verp] => 
            [Timeout] => 300
            [Timelimit] => 300
            [smtp_transaction_id_patterns:protected] => Array
                (
                    [exim] => /[0-9]{3} OK id=(.*)/
                    [sendmail] => /[0-9]{3} 2.0.0 (.*) Message/
                    [postfix] => /[0-9]{3} 2.0.0 Ok: queued as (.*)/
                )

            [smtp_conn:protected] => 
            [error:protected] => Array
                (
                    [error] => 
                    [detail] => 
                    [smtp_code] => 
                    [smtp_code_ex] => 
                )

            [helo_rply:protected] => 
            [server_caps:protected] => 
            [last_reply:protected] => 221 2.0.0 Bye

        )

    [to:protected] => Array
        (
            [0] => Array
                (
                    [0] => [email protected]
                    [1] => 
                )

        )

    [cc:protected] => Array
        (
        )

    [bcc:protected] => Array
        (
        )

    [ReplyTo:protected] => Array
        (
        )

    [all_recipients:protected] => Array
        (
            [[email protected]] => 1
        )

    [RecipientsQueue:protected] => Array
        (
        )

    [ReplyToQueue:protected] => Array
        (
        )

    [attachment:protected] => Array
        (
        )

    [CustomHeader:protected] => Array
        (
        )

    [lastMessageID:protected] => 
    [message_type:protected] => plain
    [boundary:protected] => Array
        (
            [1] => b1_ae21342e62a3234e7bbf2dea4021136c
            [2] => b2_ae21342e62a3234e7bbf2dea4021136c
            [3] => b3_ae21342e62a3234e7bbf2dea4021136c
        )

    [language:protected] => Array
        (
            [authenticate] => SMTP Error: Could not authenticate.
            [connect_host] => SMTP Error: Could not connect to SMTP host.
            [data_not_accepted] => SMTP Error: data not accepted.
            [empty_message] => Message body empty
            [encoding] => Unknown encoding: 
            [execute] => Could not execute: 
            [file_access] => Could not access file: 
            [file_open] => File Error: Could not open file: 
            [from_failed] => The following From address failed: 
            [instantiate] => Could not instantiate mail function.
            [invalid_address] => Invalid address: 
            [mailer_not_supported] =>  mailer is not supported.
            [provide_address] => You must provide at least one recipient email address.
            [recipients_failed] => SMTP Error: The following recipients failed: 
            [signing] => Signing Error: 
            [smtp_connect_failed] => SMTP connect() failed.
            [smtp_error] => SMTP server error: 
            [variable_set] => Cannot set or reset variable: 
            [extension_missing] => Extension missing: 
        )

    [error_count:protected] => 2
    [sign_cert_file:protected] => 
    [sign_key_file:protected] => 
    [sign_extracerts_file:protected] => 
    [sign_key_pass:protected] => 
    [exceptions:protected] => 1
    [uniqueid:protected] => ae21342e62a3234e7bbf2dea4021136c
)
The SMTP debugging output is shown below: