Contact Form Image Upload

My “Contact Us” form is built entirely with custom HTML / CSS and a small vanilla-PHP handler. I now need it to let visitors attach images—ideally any number over five—so they can send detailed enquiries without resorting to follow-up emails.

Here is what I expect:
• An image-upload field that supports multiple file selection (drag-and-drop is welcome if you like).
• Validation that accepts only JPEG/JPG and PNG; anything else should quietly refuse or alert the user.
• A reasonable per-file and total size check so the form doesn’t break under huge uploads.
• Server-side handling that collects the images and forwards them with the existing email the form already sends.
• Clean, commented code that slots straight into my current HTML/CSS setup without altering the design.

Once everything is in place I’ll run a quick browser test (Chrome, Firefox, Safari) and send a sample message with seven mixed images to confirm that all attachments arrive intact. When that passes, the job is done.