A well-timed, personalized notification can remind users to complete onboarding, re-engage dormant accounts, and highlight key features in a SaaS product, ultimately driving retention and long-term success. Poorly executed notifications, however, can be just as harmful as none at all, while behavior-driven notifications that highlight completed tasks or underutilized features can keep users engaged. Effective multichannel strategies, using channels such as email, SMS, in-app, push, and Slack, are crucial to reaching users where they are most likely to respond, and tools like Courier's Unified API simplify the process by streamlining message delivery across multiple platforms. By leveraging personalized onboarding, behavioral triggers, and a multi-channel approach, SaaS companies can reduce churn and boost retention rates.