Building Notification Infrastructure at Scale Is a Trap: Why Your Team Will Regret Rolling Their Own

It starts innocently. A product manager asks for email notifications when a user signs up. A backend engineer adds a sendEmail() call after the registration handler. It works. It ships. Everyone moves on. Three months later, the feature request list looks like this: send order confirmations via SMS, push a notification when a delivery is nearby, alert admins via Slack when a payment fails, batch a daily digest for inactive users, and let marketing send a promotional SMS to 200,000 opted-in customers on Black Friday. The engineer who wrote sendEmail() is now staring at a queue system, a channel router, a retry engine, a preference center, an opt-out compliance layer, and a rate limiter — none of which exist. The original ten lines of code have metastasized into an infrastructure project that will consume the next six months of a team's roadmap. This is not a contrived scenario. This is the default trajectory of notification systems in growing SaaS companies. And the reason it catches te