Hi Juri - thanks for posting!
Unfortunately, there is no way to achieve this type of MailChimp form validation for the Unbounce form at this time. The reason for this is because of how a lead is handled after a form submission. Currently the steps goes as follows:
- A lead is submitted
- The lead is collected for the Unbounce form into Unbounce
- At an unspecified time afterwards, the lead is sent through the integration to the MailChimp list
As you can see from this process, because the sending of the lead through the MailChimp integration occurs after the form submission, there is no way to feed that error back as a validation error to the form submission as it was happening.
However, I will go ahead to ensure that this thread gets changed into a feature request so that our development team can get to consider this feature for their development roadmap.
I know this isn’t exactly what you were hoping for but I hope that this helps to clarify the structure of the Unbounce to MailChimp integration a bit more. If you have any further comments or questions about this, please don’t hesitate to let us know.
Jacquelyn | Unbounce Customer Success