How do “burst sends” differ from throttled batches?

Burst sending releases all messages simultaneously at maximum speed. Your MTA attempts to deliver as fast as network and recipient servers allow. Throttled batches intentionally pace delivery, spreading messages over minutes or hours.

Burst sending risks:

Triggering rate limits at recipient servers

Overwhelming your own infrastructure

Looking like spam (sudden volume spikes)

Filling queues with deferrals

Reputation damage from aggressive patterns

Throttled sending benefits:

Stays within rate limits

Maintains steady, predictable volume patterns

Reduces deferrals by not exceeding capacity

Easier troubleshooting (problems appear gradually)

Better reputation signals

When burst sending makes sense: extremely time-sensitive messages, small volumes to good lists, or infrastructure designed for burst capacity.

When to throttle: large campaigns, warming new IPs, sending to providers with known rate limits, or maintaining consistent daily patterns.

Most ESPs throttle by default. Self-hosted senders should configure throttling in their MTA to avoid reputation damage from burst patterns.

A fleet arriving simultaneously overwhelms the port. Ships arriving in scheduled intervals process smoothly.