Rate Limiting

Definition

Rate limiting is the process of restricting the number of messages sent in a period of time to avoid overwhelming responses or to a particular person who might be in multiple segments. If you have a mega deal to announce and a lot of subscribers, a single push notification could be enough to overload your servers with traffic and put a major damper on your momentum. Better to set rate limits so that, say, only 10,000 messages send each minute, which will stagger the response.

If using rate limiting, it's important to do the math for any time or supply limited offers. Depending on your database, limits might mean that some messages won't be sent for a day or longer (5M at 10K per minute will take more than two days and the offer may be expired.) You also might want to coordinate with other delivery features, like send-time optimization or frequency caps.

Usage

Rate limiting is gaining in popularity and understanding, but still a somewhat technical concept. While the size and capability of servers has grown over time, they are still limited and as lists grow, this technique becomes increasingly important. One major overload could lead to a campaign failed for all the wrong reasons—you should be able to benefit from high demand, not be slowed by it.