S4S Cloud The Send2CRM service provides a custom form validator for verifying Google reCAPTCHA tokens.
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Set the reCAPTCHA validator on the applicable form mapping(s).
Limitations
Google reCAPTCHA tokens are single-use only. This validation cannot be used by both Salesforce and your website backend for the same submission.
For those using out-of-the-box functionality, Send2CRM will automatically halt form submissions as normal if verification fails, no further action needed. However if you need programmatic confirmation you can handle the Send2CRM submit event and test the form response for success; it will always fail if the reCAPTCHA did not verify!