UTL_SMTP is becoming slower suddenly

Question

Hi everybody,
we are using the package UTL_SMTP to send mails in our applications. Not so long ago, the email were really quick. Now it takes over 10 seconds to send 3 mails with no attachment, It's not acceptable. Do you know a way to send the mail faster ?
I read somewhere that in Oracle 10g we should use UTL_MAIL instead of UTL_SMTP ? Would it spead my mail generation ?
Thank you !
Leinad !

Answer 1

leinadjan wrote:
I think I found the culprit, it's the connection to the SMTP server. Each team the procedure is call, we open a new connection and we close it. And the average connection time is 5 seconds. This three time and we have 15 seconds to wait.Does not sound reasonable. A tcp socket connection should be faster - unless it is across (slower) WAN infrastructure.
The SMTP server could be doing reverse DNS lookups for logging purposes. It accepts a client connection. The IP address of the client is available - but instead of using that alone for logging purposes, it can lookup the hostname of that IP. And then use the hostname for logging. (it also may use it for same basic access control that is based on host and domain names),
This is called a reverse DNS lookup and can result in making the initial client connection a lot slower.
But I think I shoulld at least to try to share the connections for all mail and it will be a small gain of speed.You cannot share a socket connection across PL/SQL sessions. So if session 123 creates a SMTP connection, only it can use that connection.
What you can do is implement a basic mail send server in PL/SQL. A PL/SQL package can use any of the IPC (Inter Process Communication) methods available in Oracle for other sessions to communicate with it. E.g. database pipes, or message queues, or even just a plain vanilla SQL table.
This package can create a SMTP connection, keep it alive and dequeue any messages it receives from other Oracle sessions. A dequeued message is transformed into a mail message and the existing SMTP connection is used to send it.
This package can be run as a background process using DBMS_JOB/DBMS_SCHEDULER.
Some IPC methods supports multiple server-side processes - in which case this approach can be scaled by running something like 5 copies of this mail server code. This then supports 5 concurrent requests for sending mail. Kind of like the shared server/MTS concept in Oracle.
UTL_SMTP.close_data (v_connectionsmtp); Is that the command who finish the creation of my mail ?Correct. This sends a period and CRLF to the server to indicate that the complete e-mail has been send.
The server will respond with a numeric code (that UTL_SMTP should check for confirmation) and then the server will wait for the next SMTP command from your code.
I want to manage manually the connection, open it when it's null and close it at the end of my script....Not sure what you mean "+open it when it's null+"?
If you do create a mail send server in PL/SQL code, it should look something as follows:
connect to SMTP./mail server
send HELO command
while PLSQLServerIsActive loop
  if MessageOnQueue then
    DequeueMessage
    send MAIL FROM command
    send RCPT FROM command
    send DATA command
    send e-mail
    send period + CRLF (end-of-mail)
  end if
  if TimeIdle > 60 seconds then
    // tell the SMTP server that we're still here in order
    // to prevent it from timing us out and closing the
    // tcp connection
    send RSET command
  end if
  // shutdown when commanded to
  if ReceiveServerShutdown  then PLSQLServerIsActive := false
end loop 
send QUIT command