utl_smtp issue

I used Oracle utl_smtp to send emails. It was working very well unit two weeks ago, without my PL/SQL procedure modified. Rigth now, after running the procedure, no emails and no error msg. Please give advice. Thank you.

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PROCEDURE send_email IS
  EMSVR   varchar2(100):='111.111.11.111'; --email server IP
  ESender varchar2(50):='webMaster@myapplication.com'; --sender email
  conn UTL_SMTP.CONNECTION;
  v_UEmail varchar2(100):='myEmail@test.com'; --receiver email
  mesg VARCHAR2( 1000 );
  v_dbSvr varchar2(100);
BEGIN
   select HOST_NAME into v_dbSvr from sys.v_$instance;
   conn:= utl_smtp.open_connection( EMSVR, 25 );
   utl_smtp.helo( conn, EMSVR );
   utl_smtp.mail( conn, ESender );