The user should not wait for SMTP
When a customer submits an order or a lead form, the HTTP response should confirm success immediately. Email, SMS, and webhooks belong in queued jobs that retry when a provider is slow.
Idempotency matters
Payment and shipping partners replay callbacks. Notification jobs need keys so the warehouse does not get three texts for one order.
Schedule the boring work
Reports and imports run on the scheduler with logged exit codes. That is how automation projects stay visible when they fail at 2 a.m.