421 Too many concurrent SMTP connections; please try again later.

Question

Hi,
At first I send an email, it works fine. After i try again but this time, i get "421 Too many concurrent SMTP connections; please try again later". What do i have to do? Thanks
create or replace PROCEDURE SEND_MAIL
(name_in IN Varchar, surname_in IN Varchar, email_in IN Varchar)
IS
conn utl_smtp.connection;
BEGIN
conn := utl_smtp.open_connection ( 'mail.ppp.com', 25 ); -- SMTP database host and on port 25
utl_smtp.ehlo( conn, 'mail.ppp.com' );
utl_smtp.command(conn, 'auth login');
     utl_smtp.command(conn,UTL_RAW.CAST_TO_VARCHAR2(utl_encode.base64_encode(utl_raw.cast_to_raw('oooo'))));
     utl_smtp.command(conn,UTL_RAW.CAST_TO_VARCHAR2(utl_encode.base64_encode(utl_raw.cast_to_raw('oooo'))));
utl_smtp.mail( conn, '[email protected]' );
utl_smtp.rcpt( conn, email_in );
utl_smtp.data( conn,
'From: Rental' || utl_tcp.crlf ||
'To: ' || eremail_in || utl_tcp.crlf ||
'Subject: ' || 'Confirmation' ||
utl_tcp.crlf || 'Dear'||' '||name_in||' '||surname_in||','
||chr(13)||chr(10)||chr(13)||chr(10)||'Welcome'
utl_smtp.quit(conn);
END;
Message was edited by:
veledrom

Answer 1

Sounds like you have an exception in the code and not protecting the resource - which means resource leakage.
In your case, not closing TCP socket connections to the SMTP server. This then results in the SMTP server refusing to allow you more connections.
Or.. there is simply too many concurrent connections from different users/sessions/processes at the same time and it cannot service your connection.
PL/SQL does not specifically support a resource protection block. These are typically in the form of:
allocate resource;
try
use resource;
finally
release resource;The intention being that should sosmething go pear shape while using that resource, the resource is protected and released - thus preventing that resource from leaking all over the code and the server.
In PL/SQL we can only achieve this by creating an exception handler, releasing the resource (if allocated) and then re-raising the exception.
Suggest that you consider this approach whenever you allocate anything in PL/SQL - from a TCP socket handle to LOB locater or ref cursor.