ORA-29024: Certificate validation failure using smtp-relay.gmail.com in utl_smtp

We are planning to use smtp-relay.gmail.com for sending emails through utl_smtp procedure. While doing so, we are getting "ORA-29024: Certificate validation failure". Did anyone face this before. If so can you please share you expertise that will be very much help

Testing code

• DECLARE
•  c       utl_smtp.connection;
•  v_host    varchar2(200)    := 'smtp-relay.gmail.com';
•  v_port    varchar2(10)    := '587';
•  v_username  varchar2(100)    := 'googlesmtprelay@xyz.com';
•  v_password  varchar2(100)    := ' xyz';
•  v_wallet_dir varchar2(128)    := 'S3_SSL_WALLET';
•  v_wallet_path varchar2(4000);
• BEGIN
•  
• c := utl_smtp.open_connection( host     => v_host
•                  ,port    => v_port
•                  ,wallet_path => 'file:Wallet_path'