S4D will automatically send detailed error email messages when the Save To Dynamics Submit Action experiences a fatal error, provided that the email settings are correctly configured.
Emails include:
Configuration. The Submit Action properties defined on the form.
Mapped form values. The fields mapped to the Dynamics entity including values submitted.
Log messages. Logs from all levels regardless of the current Sitecore logging settings, that occurred during the Submit Action execution. Limited to the the last 100 lines.