Shopify API: How do I send customer an email about product being shipped?

I'm trying to send a customer an email with order tracking information by updating the order fulfillment but the email is not being sent out. I can retrieve the fulfillment and add a tracking code and it saves properly but the status doesn't update.

 fulfillment_id = 3252574519475
 shopify_order_id = 3683332686003

 fulfillment = shopify.Fulfillment.find(fulfillment_id,order_id=shopify_order_id)
 fulfillment.tracking_numbers = [tracking_number]
 fulfillment.tracking_company = tracking_company
 fulfillment.notify_customer = "true"
 fulfillment.status = "success"
 fulfillment.shipment_status = "delivered"
 result = fulfillment.save()

When I visit https://dev-store.myshopify.com/admin/orders/3683332686003/fulfillments.json I see the tracking_numbers update along with the tracking_company and tracking_urls but the status is still open:

 {
    "fulfillments": [{
        "id": 3252573110451,
        "order_id": 3683332686003,
        "status": "success",
        "created_at": "2021-03-22T14:36:55-04:00",
        "service": "gift_card",
        "updated_at": "2021-03-22T14:36:56-04:00",
        "tracking_company": null,
        "shipment_status": null,
        "location_id": 61514940595,
        "line_items": [{
            "id": 9689309610163,
            "variant_id": 39396209983667,
            "title": "$100 ta E-Gift Card",
            "quantity": 1,
            "sku": null,
            "variant_title": "$100.00 USD",
            "vendor": "A",
            "fulfillment_service": "gift_card",
            "product_id": 6571217256627,
            "requires_shipping": false,
            "taxable": false,
            "gift_card": true,
            "name": "$100 ta E-Gift Card - $100.00 USD",
            "variant_inventory_management": null,
            "properties": [],
            "product_exists": true,
            "fulfillable_quantity": 0,
            "grams": 0,
            "price": "95.00",
            "total_discount": "0.00",
            "fulfillment_status": "fulfilled",
            "price_set": {
                "shop_money": {
                    "amount": "95.00",
                    "currency_code": "USD"
                },
                "presentment_money": {
                    "amount": "95.00",
                    "currency_code": "USD"
                }
            },
            "total_discount_set": {
                "shop_money": {
                    "amount": "0.00",
                    "currency_code": "USD"
                },
                "presentment_money": {
                    "amount": "0.00",
                    "currency_code": "USD"
                }
            },
            "discount_allocations": [],
            "tax_lines": []
        }],
        "tracking_number": null,
        "tracking_numbers": [],
        "tracking_url": null,
        "tracking_urls": [],
        "receipt": {
            "gift_cards": [{
                "id": 483988799667,
                "line_item_id": 9689309610163,
                "masked_code": "•••• •••• •••• 74e2"
            }]
        },
        "name": "#1013.1"
    }, {
        "id": 3252574519475,
        "order_id": 3683332686003,
        "status": "open",
        "created_at": "2021-03-22T14:37:23-04:00",
        "service": "manual",
        "updated_at": "2021-03-22T14:49:45-04:00",
        "tracking_company": "UPS",
        "shipment_status": null,
        "location_id": 61514940595,
        "line_items": [{
            "id": 9689309642931,
            "variant_id": 39396224663731,
            "title": "The Pack",
            "quantity": 1,
            "sku": "FM-001",
            "variant_title": null,
            "vendor": "A",
            "fulfillment_service": "manual",
            "product_id": 6571220402355,
            "requires_shipping": true,
            "taxable": true,
            "gift_card": false,
            "name": "The Pack",
            "variant_inventory_management": null,
            "properties": [],
            "product_exists": true,
            "fulfillable_quantity": 0,
            "grams": 3629,
            "price": "111.99",
            "total_discount": "0.00",
            "fulfillment_status": null,
            "price_set": {
                "shop_money": {
                    "amount": "111.99",
                    "currency_code": "USD"
                },
                "presentment_money": {
                    "amount": "111.99",
                    "currency_code": "USD"
                }
            },
            "total_discount_set": {
                "shop_money": {
                    "amount": "0.00",
                    "currency_code": "USD"
                },
                "presentment_money": {
                    "amount": "0.00",
                    "currency_code": "USD"
                }
            },
            "discount_allocations": [],
            "tax_lines": []
        }],
        "tracking_number": "1Z6R96W802851935",
        "tracking_numbers": ["1Z6R96W802851935"],
        "tracking_url": "https:\/\/www.ups.com\/WebTracking?loc=en_US\u0026requester=ST\u0026trackNums=1Z6R96W80302851935",
        "tracking_urls": ["https:\/\/www.ups.com\/WebTracking?loc=en_US\u0026requester=ST\u0026trackNums=1Z6R96W80302851935"],
        "receipt": {},
        "name": "#1013.2"
    }]
 }
 

How do I get shopify to send the customer an email with the tracking number and update the status of the fulfillment from open to success so that the whole order is set to fulfilled? I've been manually creating orders on the store im not sure if that has anything to do with it.

I'm using this Python package https://github.com/Shopify/shopify_python_api

from Shopify API: How do I send customer an email about product being shipped?