Sendy is open source (albeit not free) and running on your own server. Ben's response says because you are using a customized webform instead of sendy's provided forms, that you need to handle the captcha code on the form and siteverify on the backend on your own.
Before sendy had recaptcha support you would have to modify the subscribe code to include a call to captcha siteverify. Here's some PHP code for how you call siteverify before proceeding with something:
You can avoid running your own backend altogether now anyway since SES supports bulk template emails. You can store all your form submissions using a lambda/cloudfunction/webworker to verify the captcha and store the list. When you want to send email you can pull your list into something running on your laptop and then invoke the SES bulk templated email from there. You can use lambdas for pixels and custom links that update records for those users. I wrote my own angular-firebase version of this
if captcha fails:
feedback = "Failed recaptcha test"
if you need API support, you could use captcha_passed = verify_api_key($api_key) and include the api_key in the post request
According to what or who? It ships with laughably obfuscated files, it makes no mention of open source in any documentation.
How does that work? What's the license exactly?
> This Agreement grants a non-exclusive, non-transferable license to install and use the Software on a single Website. Additional Software licenses must be purchased in order to install and use the Software on additional Websites. The Author reserves the right to determine whether use of the Software qualifies under this Agreement. The Author owns all rights, title and interest to the Software (including all intellectual property rights) and reserves all rights to the Software that are not expressly granted in this Agreement.
> [...] You may not:
> Distribute derivative works based on the Software;
> Reproduce the Software except as described in this Agreement;
OP might mean source accessible (rather than compiled or being a hosted service).