We would like to enfoce a rule that only work emails are allowed for marketing form submissions. Is that possible and if so, how?

We would like to enfoce a rule that only work emails are allowed for marketing form submissions. Is that possible and if so, how?
Hi,
Yes it is, you have to do a custom validation at formSubmit event by marketing form API.
Here more information:
Extend marketing forms using code (Dynamics 365 Marketing Developer Guide) | Microsoft Docs
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