The formal documents for the SMTP setup:
https://coder.com/docs/@v2.18.2/admin/monitoring/notifications#smtp-email

The UI's page: /deployment/notifications?tab=settings

It would be beneficial to see closer alignment in which settings are Required.

The UI's version may also benefit the SMARTHOST to be updated from CODER_NOTIFICATIONS_EMAIL_FORCE_TLS to CODER_EMAIL_SMARTHOST (Unless this is fixed in 2.18.3).

Also, the UI version could benefit with CODER_EMAIL_SMARTHOST:PORT (since the PORT is also Required)