Rate Limits

Send limits and cold outreach throttling

openmail enforces rate limits to protect domain reputation and ensure deliverability for all customers.

Send limits

Limit	Value	Scope
Burst	10/minute	Per inbox
Daily	200/day	Per inbox
Inbox creation	100/day	Per account

Cold outreach throttle

A “cold” send is an email to a recipient who has never sent an inbound message to this inbox. Cold sends have additional limits:

Inbox age	Cold send limit
First 30 days	20/day per inbox
After 30 days	Standard daily limit (200/day)

This protects your domain reputation while it warms up. Relationship email (replies to existing threads) is not affected.

Rate limit responses

When rate limited, the API returns 429 with a Retry-After header:

{
  "error": "rate_limit_exceeded",
  "message": "Max 10 sends per minute per inbox"
}

Why this matters

Fresh domains on shared IP pools need time to build reputation. If your agents send too much cold outreach too quickly, emails will land in spam — which hurts your agents’ effectiveness and your domain’s reputation. These limits exist to protect deliverability.

Contact us if you need higher limits or a dedicated sending IP.