The documentation for SendgridToolkit::ListEmails says you can add single recipients to a list, or an array of recipients, but adding an array doesn't seem to work:
abstract_sendgrid_client.rb:17 forces all data into the URL. It's a POST request, and data should be in the body instead of the URL. It works, but you're limited to a few thousand characters instead of a thousand recipients.
- The data is getting serialized strangely.
data: [{a:1,b:2}, {a:3,c:4}] becomes data[][a]=1&data[][b]=2&data[][a]=3&data[][c]=4 instead of data[]=%7B%22a%22%3A1%2C%22b%22%3A2%7D&data[]=%7B%22a%22%3A3%2C%22c%22%3A4%7D
Sendgrid responds with {"error": "error in data: data is required"}
Edit: Looks like you've already switched HTTParty.post(..., query => ... to HTTParty.post(..., body => ..., but the gem hasn't been updated?