Rate Limiting (Leaky Bucket):

For tasks that require a perfectly steady flow (like an email sender), a "bursty" traffic pattern can overwhelm the downstream service. This "spiky load" is a common cause of 429 "Too Many Requests" errors. The Leaky Bucket algorithm "drips" requests at a constant, fixed rate, regardless of how fast they come in. It turns a chaotic traffic flow into a predictable, smooth stream.