Sending limits

Domains and inboxes and sending quotas are different: unlimited inboxes do not mean unlimited sending.

Subscription-and-usage plans

On the paid plan, 500 outgoing recipients are included per billing month. Extra sending is prepaid at $0.003 per recipient: buy 2,000 recipients for $6 + VAT in Settings → Billing. Billing shows included usage, prepaid balance and pending reservations. An app warning appears with 100 or fewer available sends. Empty balances stop sending before the provider is called.

Only provider-accepted recipients consume prepaid credit permanently. Unconfirmed attempts reserve credit until resolved. Usage months follow the subscription billing date in UTC, including annual subscriptions. Receiving includes 5,000 mailbox deliveries per billing month, then $0.0005/delivery, funded with separate prepaid receiving credit. 5 GB shared storage, anti-abuse and provider safeguards still apply. See receiving usage. Unused prepaid sends carry over and require an active subscription. New prepaid usage is never reported to Stripe as an additional metered invoice.

The free plan uses the rolling limits described below and is never charged overage.

Free plan sending

The free plan includes 50 recipient deliveries per rolling 30 days, with at most 20 per rolling 24 hours, shared across both inboxes and all API keys. See the free plan details. Each To, Cc, Bcc, forwarding copy and forwarding-verification recipient counts. An email sent to three recipients uses three deliveries.

The Sending meter on Settings → Billing shows used and remaining capacity. A compact app warning appears at 80% and stays visible when the limit is reached. The app refreshes usage after sends and every minute while visible, including sends from API clients and agents.

The window rolls continuously: older sends stop counting after 30 days. It does not reset on the first of the month or on a billing date. Failed or uncertain attempts reserved before the provider call can count. Reservations are atomic; concurrent sends cannot spend the same remaining capacity. Deleting messages does not refund new sending reservations. Older mail from before this ledger was introduced is counted from the available Sent history.

For more sending, upgrade in Billing. No sending add-on is charged automatically. Complimentary accounts have no monthly subscription cap; provider and anti-abuse safeguards still apply.

Safety safeguards

Production configuration and individual credential safety limits may differ. Settings → API keys shows each key’s limit; Billing shows the account allowance and credit. A key’s daily safeguard never adds to or overrides the shared monthly quota. These are safeguards, not measured infrastructure capacity or guaranteed daily delivery.

A rolling window is not a midnight reset. Older sends gradually leave the previous 24 hours. Web-composer queued messages also need quota when dispatch occurs.

Other requirements

Every workspace can send within the free plan's limits; beyond them, sending needs a paid subscription or complimentary access. It also needs a sending-ready domain, mailbox access and an unblocked recipient. Suspension, provider review or provider quotas can still prevent sending.

The service’s Postmark plan and account approval are managed by the operator, not each customer. Test-mode restrictions can apply even after a customer domain verifies. No app setting overrides those restrictions.

If you reach a limit

Wait for earlier sends to leave the window or ask the operator about an appropriate limit. Creating more API keys does not bypass the shared organization quota. Adding domains or inboxes does not increase it.

API responses use 429 for rate limits and 402 for payment or paid-capacity requirements. See using the API.