I am trying to integrate Microsoft Office365 Outlook's SMTP with Oracle Apex 22.1(Running on Amazon RDS for Oracle 19c).
I have used the following configuration on Apex:
SMTP server name: smtp.office365.com
SMTP port: 587
Username: <my-email-id@outlook.com>
Password: <generated App password after 2 factor authentication>
use TLS: Yes

I have uploaded the correct MS root and intermediate certificates to the auto-login wallet and created required Netwrok ACLs.
When I try to send email using Apex (SQLPLUS), I do not get any error but the email never reaches the inbox instead the MAIl QUEUE in Apex gets populated.

begin
apex_util.set_security_group_id (p_security_group_id => 5140893825405459);
APEX_MAIL.SEND(p_from => 'awsrahul2024@outlook.com',
p_to => 'awsrahul2024@outlook.com',
p_subj => 'Test Mail2',
p_body => 'This is a test email');
apex_mail.push_queue();
END;
/

PL/SQL procedure successfully completed.

When I try to validate the email configuration, I get the following error.

SQL> begin
APEX_INSTANCE_ADMIN.validate_email_config;
end; 2 3
4 /
begin
*
ERROR at line 1:
ORA-29279: SMTP permanent error: 535 5.7.139 Authentication unsuccessful, basic
authentication is disabled. [BM1P287CA0002.INDP287.PROD.OUTLOOK.COM
2025-05-21T21:47:12.528Z 08DD989AFE00C8F6]
ORA-06512: at "APEX_220100.WWV_FLOW_MAIL", line 1284
ORA-06512: at "SYS.UTL_SMTP", line 57
ORA-06512: at "SYS.UTL_SMTP", line 142
ORA-06512: at "SYS.UTL_SMTP", line 446
ORA-06512: at "APEX_220100.WWV_FLOW_MAIL", line 1268
ORA-06512: at "APEX_220100.WWV_FLOW_MAIL", line 2588
ORA-06512: at "APEX_220100.WWV_FLOW_INSTANCE_ADMIN", line 1671
ORA-06512: at line 2


Kindly advise. Thank you!