Quotas for Google Services Google spreadsheet is awesome and completely free tool. But, it have some quotas on services. Email recipients – its count how many emails app can send during 24 hours. Each google user can do 100 emails on free account, and 1500 emails on buisness account. More about quotas Get email recipients per day programmatically
Use class \Magento\Customer\Model\ResourceModel\Customer\CollectionFactory for loading customers collection. Method addAttributeToFilter for filtering
If need update product attribute at existing product normal way it will take much time to save. Example of usual code(take lot of time for saving): Example code for speed up product update attribute: Script for testing speed: Resource – https://mage2-blog.com/magento-2-speed-up-product-save/
Use class \Magento\CatalogInventory\Api\StockRegistryInterface Load item by its sku, then update it status
Use class \Magento\CatalogInventory\Api\StockRegistryInterface Load item by its sku, then update it qty.