PL/SQL UTL_SMTP.CLOSE_DATA

The UTL_SMTP.CLOSE_DATA function is part of Oracle’s PL/SQL UTL_SMTP package, which allows interaction with SMTP (Simple Mail Transfer Protocol) servers to send emails. This particular function is used to finalize the transmission of the email body and signal to the SMTP server that the data stream is complete.

UTL_SMTP.CLOSE_DATA concludes the data segment of the SMTP transaction after the email body has been written using UTL_SMTP.WRITE_DATA. It tells the SMTP server that no more email content is forthcoming and prepares for the next phase in the SMTP conversation.

Syntax

UTL_SMTP.CLOSE_DATA (c IN OUT NOCOPY UTL_SMTP.CONNECTION);

Parameters:

c: This is the SMTP connection handle, which must have been initialized using UTL_SMTP.OPEN_CONNECTION.

Usage

The general workflow for sending an email using UTL_SMTP involves:

Establishing a connection to the SMTP server with UTL_SMTP.OPEN_CONNECTION.
Initiating a mail transaction with UTL_SMTP.MAIL and UTL_SMTP.RCPT.
Writing the email data using UTL_SMTP.WRITE_DATA.
Finalizing the email content using UTL_SMTP.CLOSE_DATA.
Closing the connection using UTL_SMTP.QUIT.

Example

Here’s a simple PL/SQL example that demonstrates the use of UTL_SMTP.CLOSE_DATA:

DECLARE
   smtp_conn  UTL_SMTP.CONNECTION;
   sender     VARCHAR2(50) := '[email protected]';
   recipient  VARCHAR2(50) := '[email protected]';
   mail_host  VARCHAR2(50) := 'smtp.example.com';
   mail_port  NUMBER       := 25;
   message    VARCHAR2(4000);
BEGIN
   -- Open connection to the SMTP server
   smtp_conn := UTL_SMTP.OPEN_CONNECTION(mail_host, mail_port);

   -- Initiate the SMTP conversation
   UTL_SMTP.HELO(smtp_conn, 'localhost');

   -- Specify the sender and recipient
   UTL_SMTP.MAIL(smtp_conn, sender);
   UTL_SMTP.RCPT(smtp_conn, recipient);

   -- Start the mail body
   UTL_SMTP.OPEN_DATA(smtp_conn);
   message := 'Subject: Test Email' || UTL_TCP.CRLF ||
              UTL_TCP.CRLF ||
              'This is a test email sent using UTL_SMTP in Oracle PL/SQL.';
   UTL_SMTP.WRITE_DATA(smtp_conn, message);

   -- Finalize the data transmission
   UTL_SMTP.CLOSE_DATA(smtp_conn);

   -- Close the SMTP connection
   UTL_SMTP.QUIT(smtp_conn);

   DBMS_OUTPUT.PUT_LINE('Email sent successfully.');
EXCEPTION
   WHEN OTHERS THEN
      IF smtp_conn IS NOT NULL THEN
         UTL_SMTP.QUIT(smtp_conn);
      END IF;
      RAISE;
END;
/

Key Points

Error Handling: Always wrap SMTP interactions in a BEGIN…EXCEPTION block to handle any errors and ensure resources are freed properly.

Order of Commands: UTL_SMTP.CLOSE_DATA should only be called after writing the email content with UTL_SMTP.WRITE_DATA. It cannot be called without prior initiation of data with UTL_SMTP.OPEN_DATA.

Compliance: Ensure that the SMTP server settings (host, port, and security protocols) are properly configured and accessible from the Oracle database.

By properly using UTL_SMTP.CLOSE_DATA, you ensure that the email content is correctly transmitted to the SMTP server, minimizing the risk of malformed or incomplete messages.