Hi @AndrewinKC,
This is definitely possible however it will require some degree of development in order to hook up a HubSpot form to an external service. There are 2 primary ways you can achieve this:
1) Forms API
I've done this using our Forms API and the Kickbox API to check/verifiy an email address. You can see this in action here if you enter an email address into the field and then click on another field: http://dev.jackcoldrick.com/kickbox-validation/. I output the response from Kickbox for demonstrative purposes. Of course in a real world scenario you wouldn't do this but rather parse the response and decide on the best course of action i.e whether to submit the form or not.
2) Customize the form embed code
You could also do something similar using our embedded forms. There is documentation on how to customize the form embed code using "advanced form options". Whilst I don't have an example of this method the process would look something like this:
- Form loaded onto page
- email address entered into the email field
- AJAX request made to third party script to verify email address
- Response returned
- If all good submit form
- If issues show error and do not submit the form
Both would require some development but depending on what you are trying to do and the level of comfort you have with this type of thing it should be fairly simple.
I hope this helps,
Jack
