Support for direct use of SMTP and Javascript

I’m now getting desperate. After weeks of futile attempts to get the SendGrid API code working for my website unico.org, I am still unable to reliably send email messages from a database form. While I was able to send test messages, others who tried got no response. Unless this is a “gotcha” which can only be remedied by a SendGrid upgrade I clearly need an alternative method.

I have the credentials to use the SMTP server I used in the previous version of the site (active server pages - that’s how old it was) in server-side VBScript code. I need a way to emulate that method. There is a site SMTPJS.com which provides code examples for using JavaScript to achieve the same purpose, but it assumes a “normal” web page where you can include remote .js files and build your forms the old-fashioned way using HTML.

I need a way to do this in Wix. I have an unhappy-rapidly-moving-to-angry client who is putting the screws to me to get this working. Please provide the necessary code examples for how this can be done ASAP.