SQL & PL/SQL

Hello everyone

I have a Stored Procedure for sending emails but error

CREATE OR REPLACE PROCEDURE send_email (
   p_recipient IN VARCHAR2,
   p_subject IN VARCHAR2,
   p_message IN VARCHAR2
) AS
   l_mailhost VARCHAR2(255) := 'smtp.gmail.com';
   l_port     NUMBER := 587; 
   l_mail_conn UTL_SMTP.connection;
   l_username  VARCHAR2(255) := 'example@gmail.com'; 
   l_password  VARCHAR2(255) := 'example'; 
   l_response  VARCHAR2(32767);
BEGIN
   l_mail_conn := UTL_SMTP.open_connection(l_mailhost, l_port);
   
   UTL_SMTP.helo(l_mail_conn, l_mailhost);
   UTL_SMTP.starttls(l_mail_conn, 'NO_CERTIFICATE_VERIFY');
   
   UTL_SMTP.write_data(l_mail_conn, 'AUTH PLAIN '  UTL_ENCODE.base64_encode(UTL_RAW.cast_to_raw(l_username  CHR(0)  l_username  CHR(0)  l_password))  UTL_TCP.CRLF);
   
   UTL_SMTP.open_data(l_mail_conn);
   UTL_SMTP.write_data(l_mail_conn, 'From: '  l_username  UTL_TCP.CRLF);
   UTL_SMTP.write_data(l_mail_conn, 'To: '  p_recipient  UTL_TCP.CRLF);
   UTL_SMTP.write_data(l_mail_conn, 'Subject: '  p_subject  UTL_TCP.CRLF);
   UTL_SMTP.write_data(l_mail_conn, UTL_TCP.CRLF); -- Blank line to separate headers from body
   UTL_SMTP.write_data(l_mail_conn, p_message || UTL_TCP.CRLF);
   
   UTL_SMTP.close_data(l_mail_conn);
   UTL_SMTP.quit(l_mail_conn);
   
   DBMS_OUTPUT.put_line('Email sent successfully to ' || p_recipient);
EXCEPTION
   WHEN OTHERS THEN
       BEGIN
           UTL_SMTP.quit(l_mail_conn);
       EXCEPTION
           WHEN OTHERS THEN
               NULL;
       END;
       RAISE;
END send_email;

why error certificate validation failure, Is there a special setting for the oracle stored procedure send email?

I just need to send some emails but not get spammed and make sure they were successfully sent.

Can someone help me solve this problem please.

Thanks