New mailbox sending ramp: use readiness gates instead of a universal schedule

Define the decision

A new mailbox is not ready merely because credentials work. It needs a recognizable identity, aligned authentication, working replies and suppression, plus an audience whose relevance has been reviewed.

Work through the procedure

1. Complete a controlled send, reply and opt-out test.
2. Start with a small reviewed cohort that the team can handle manually.
3. Reserve capacity for follow-ups and other mailbox activity.
4. Increase only after reviewing failures and responses; pause when a release gate fails.

Worked example

The following is a synthetic example for this procedure, not a customer result or performance benchmark.

Gate 1: authentication and reply path verified
Gate 2: first reviewed cohort has no unresolved sending failures
Gate 3: follow-up capacity and reply ownership remain available
Expansion decision: based on these observations, not mailbox age alone

Read the result

The plan is deliberately conditional. Provider limits are ceilings, not recommended outreach targets, and a successful connection test does not justify filling the entire available quota.

Check before moving on

1. Include warmup and ordinary business mail in the capacity review.
2. Record a pause condition and the person responsible for acting on it.

Limits and next action

This is an operational planning method, not a guaranteed safe daily volume. Use the mailbox provider’s current restrictions and the deployed application’s counters.

Source: Zintara warmup and mailbox readiness context