Enable network service (ACL) and Send mail from APEX

Enabling Network Service: By default, the ability to interact with network services is disabled in Oracle Database 11g. Therefore, you must use the BMS_NETWORK_ACL_ADMIN package to grant connect privileges to any host for the APEX_040200 database user:

DECLARE
  ACL_PATH VARCHAR2(4000);
BEGIN
    -- Look for the ACL currently assigned to '*' and give APEX_040200
    -- the "connect" privilege if APEX_040200
    -- does not have the privilege yet.
  SELECT ACL INTO ACL_PATH FROM DBA_NETWORK_ACLS
    WHERE HOST = '*' AND LOWER_PORT IS NULL AND UPPER_PORT IS NULL;
  IF DBMS_NETWORK_ACL_ADMIN.CHECK_PRIVILEGE (ACL_PATH,'APEX_040200','connect') IS NULL THEN
    DBMS_NETWORK_ACL_ADMIN.ADD_PRIVILEGE(ACL_PATH,'APEX_040200', TRUE, 'connect');
  END IF;
  EXCEPTION
    -- When no ACL has been assigned to '*'.
  WHEN NO_DATA_FOUND THEN
    DBMS_NETWORK_ACL_ADMIN.CREATE_ACL('power_users.xml',
    'ACL that lets power users to connect to everywhere',
    'APEX_040200', TRUE, 'connect');
  DBMS_NETWORK_ACL_ADMIN.ASSIGN_ACL('power_users.xml','*');
END;
/
COMMIT;

Send Mail: Oracle application express send mail using APEX_MAIL package. example…

APEX_MAIL.SEND(
        p_to        => '[email protected]',
        p_from      => '[email protected]',
        p_subj      => 'APEX_MAIL with attachment',
        p_body      => 'Please review the attachment.',
        p_body_html => '<b>Please</b> review the attachment');
/

Send mail with attachments…

DECLARE
    l_id Number;
    x varchar2(100);
    y BLOB;
    z varchar2(100);
BEGIN
    l_id := APEX_MAIL.SEND(
        p_to        => '[email protected]',
        p_from      => '[email protected]',
        p_subj      => 'APEX_MAIL with attachment',
        p_body      => 'Please review the attachment.',
        p_body_html => '<b>Please</b> review the attachment');

    SELECT FILENAME, IMAGE, MIMETYPE into x, y, z
        FROM CUSTOMER
        WHERE CUSTOMER_ID = 100;

        APEX_MAIL.ADD_ATTACHMENT(
            p_mail_id    => l_id,
            p_attachment => y,   -- BLOB column name
            p_filename   => x,   -- File Name 
            p_mime_type  => z);  -- MIME column name
END;
/