Checkbox Field in Contact Form 7
Allow multi-select options with `[checkbox]` / `[checkbox*]`.
Allow multi-select options with `[checkbox]` / `[checkbox*]`.
Accept uploads with `[file]` / `[file*]` and limit types/sizes.
Pass context with `[hidden]` tags (campaign, page URL, product ID).
Collect longer messages with `[textarea]` / `[textarea*]`.