How can I split apart an email with a multipart/related MIME type using a boundary?

I saw this great question and answer on StackOverflow on embedding an image in an email. Unfortunately, the answerer didn't explain how to split the email with a boundary - he said he didn't know what the boundary was for.

This is what I tried:

    v_body := '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
  <head>  
    <meta http-equiv="content-type" content="text/html; charset=ISO-8859-15"> 
  </head> 
  <body bgcolor="#ffffff" text="#000000"> 
    <img src="data:image/jpg;base64,------------090303020209010600070908' || v_image || '------------090303020209010600070908" /> 
  </body> 
</html>'; 

utl_mail.send('myemail.example.com', 
              'myemail.example.com',
              null,
              null, 
              'Image attachment test',
              v_body,
              'multipart/related; boundary="------------090303020209010600070908"',
              null);

It sends the base64 string as raw characters instead of converting it into an image.

Then, I tried:

    v_body := 'This is a multi-part message in MIME format. 
--------------090303020209010600070908 
Content-Type: text/html; charset=ISO-8859-15 
Content-Transfer-Encoding: 7bit 

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
  <head> 

    <meta http-equiv="content-type" content="text/html; charset=ISO-8859-15"> 
  </head> 
  <body bgcolor="#ffffff" text="#000000"> 
    <img src="cid:part1.06090408.01060107" alt=""> 
  </body> 
</html> 

--------------090303020209010600070908 
Content-Type: image/png; 
 name="moz-screenshot.png" 
Content-Transfer-Encoding: base64 
Content-ID: <part1.06090408.01060107> 
Content-Disposition: inline; 
 filename="moz-screenshot.png" 

' || v_image || '

--------------090303020209010600070908-- '; 

utl_mail.send('myemail.example.com', 
              'myemail.example.com',
              null,
              null, 
              'Image attachment test',
              v_body,
              'multipart/related; boundary="------------090303020209010600070908"',
              null);

The email content was not visible this time.

So, how can we split apart an email with a multipart/related MIME type using a boundary in Oracle?

Solution

I have used utl_smtp package:

procedure send_email (
    p_image blob
    )
  is
    conn utl_smtp.connection;
    BOUNDARY  VARCHAR2 (256) := '-----090303020209010600070908';
    i         pls_integer;
    len       pls_integer;
    buff_size pls_integer := 57;
    l_raw     raw(57);
  begin

conn := UTL_SMTP.open_connection (smtp_host, smtp_port);
UTL_SMTP.helo (conn, smtp_domain);
UTL_SMTP.mail (conn, 'myemail@example.com');
UTL_SMTP.rcpt (conn, 'myemail@example.com');
UTL_SMTP.open_data (conn);
UTL_SMTP.write_data (conn, 'From' || ': ' || 'myemail@example.com'|| UTL_TCP.CRLF);
UTL_SMTP.write_data (conn, 'To' || ': ' || 'myemail@example.com'|| UTL_TCP.CRLF);
UTL_SMTP.write_data (conn, 'MIME-Version: 1.0' || CHR (13) || CHR (10));
UTL_SMTP.write_data (conn, 'Content-Transfer-Encoding: 8bit' || CHR (13) || CHR (10));
UTL_SMTP.write_data (conn, 'Subject: image in attachment' || CHR (13) || CHR (10) ) ;
UTL_SMTP.write_data (conn, 'Content-Type: multipart/mixed; boundary="' || BOUNDARY || '"' || UTL_TCP.CRLF);
UTL_SMTP.write_data (conn, 'X-Mailer:Mailer by Oracle UTL_SMTP');
UTL_SMTP.write_data (conn, UTL_TCP.CRLF);
UTL_SMTP.write_data (conn, 'This is a multi-part message in MIME format.' || UTL_TCP.crlf);
UTL_SMTP.write_data (conn,  '--' || BOUNDARY || UTL_TCP.CRLF );
UTL_SMTP.write_data (conn,  'Content-Type: text/html; charset="windows-1251"'|| UTL_TCP.CRLF );
UTL_SMTP.write_data (conn, UTL_TCP.CRLF);
UTL_SMTP.write_data (conn, 'put your html code here');
UTL_SMTP.write_data (conn, UTL_TCP.CRLF);
UTL_SMTP.write_data (conn,  '--' || BOUNDARY || UTL_TCP.CRLF );
UTL_SMTP.write_data (conn,  'Content-Type: image/jpeg;'|| UTL_TCP.CRLF );
UTL_SMTP.write_data (conn, 'Content-Disposition: inline; filename="image.jpg"' || UTL_TCP.CRLF);
UTL_SMTP.write_data (conn, 'Content-Transfer-Encoding' || ': ' || 'base64' || UTL_TCP.CRLF);
UTL_SMTP.write_data (conn, 'Content-ID: <part1.06090408.01060107>'); 
UTL_SMTP.write_data (conn, UTL_TCP.CRLF);
UTL_SMTP.write_data (conn, UTL_TCP.CRLF);

i := 1;
len := dbms_lob.getlength(p_image);
while i < len
loop
  dbms_lob.read(p_image, buff_size, i, l_raw);
  utl_smtp.write_raw_data(conn, utl_encode.base64_encode(l_raw));
  utl_smtp.write_data(conn, utl_tcp.crlf);
  i := i + buff_size;
end loop;
utl_smtp.write_data(conn, utl_tcp.crlf);
    UTL_SMTP.write_data (conn, '--' || BOUNDARY || '--' || UTL_TCP.CRLF);

UTL_SMTP.write_data (conn, UTL_TCP.CRLF);
UTL_SMTP.close_data (conn);
UTL_SMTP.quit (conn);

end;