Risky is not the same as invalid
Disposable inboxes, role accounts (info@, admin@), and accept-all domains often return uncertain mailbox-level answers. They can still receive mail—or bounce later.
Keep risky separate from undeliverable so you can apply channel-specific rules.
Choose rules by business context
B2B SaaS may accept role addresses for trials. Consumer ecommerce may reject disposable inboxes at checkout.
Monitor downstream engagement and abuse to refine the policy over time.