To configure and enable sending emails from an OCI ADB database, review this post:
https://blogs.oracle.com/apex/post/sending-email-from-your-oracle-apex-app-on-autonomous-database
It may seem that it only applies to APEX applications - that's not true - it enables sending emails from any PLSQL code in your ADB.
The APEX schema is automatically included in all provisioned ADBs - and with it comes multiple useful utility functions, not least of which is APEX_EMAIL allowing us to send emails from any PLSQL code.
A note to Always Free subscribers wishing to enable sending emails in their second ADB - the exact same set of APEX_INSTANCE_ADMIN.SET_PARAMETER commands apply to both ADBs instances, for example:
BEGIN
APEX_INSTANCE_ADMIN.SET_PARAMETER('SMTP_HOST_ADDRESS', 'smtp.email.uk-london-1.oci.oraclecloud.com');
APEX_INSTANCE_ADMIN.SET_PARAMETER('SMTP_USERNAME', 'ocid1.user.oc1..aaaaaaaaxa4jjnjuqznwm2xayyrpdqwc6pauj2axv22c6weakvuq7ik5jujq@ocid1.tenancy.oc1..aaaaaaaav2n7ggsssgyd54ieic2umz24enqyubi6boqce4lkksbskayn6f6q.g3.com');
APEX_INSTANCE_ADMIN.SET_PARAMETER('SMTP_PASSWORD', 'N+Mtwq)US<Hzs{.L$MV1');
COMMIT;
END;
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The ability to send emails from PLSQL is another generous offering within the Always Free plan. You can send up to 100 emails a day up to a limit of 3000 month.
We use it in the CMS to automatically email visit and performance summaries to each website owner that has deployed to a custom domain.