What is throttling, and why is it important for deliverability?

Throttling means limiting how fast you send emails. It's essential for cold email because mailbox providers monitor sending velocity as a spam indicator.

Why throttling matters:

Sudden volume spikes trigger defensive filtering

Human senders don't send 100 emails per minute

Receiving servers impose rate limits and reject excessive connections

Gradual sending distributes load and appears more natural

How throttling works:

Spread daily volume across business hours

Add random delays between individual sends

Respect per-domain limits (don't send 50 messages to the same company simultaneously)

Adjust based on bounce and deferral signals

Practical implementation: Most cold email tools handle throttling automatically. Configure sending schedules that span several hours. If you see 421 rate limit errors, you're sending too fast.

A ship entering harbor at full speed raises alarms. Approaching at measured pace signals legitimate intentions.