Startup includes 50 mailboxes. Enterprise includes 200. Pre-warmed marketplace mailboxes count as a separate pool (not against your plan cap). If you need more mailboxes than your plan includes, buy email-user credits at $1/mailbox/month (available under Settings → Subscription) or upgrade to Enterprise.
What's included by plan
- Startup: 50 mailboxes base. Can add credits to increase.
- Enterprise: 200 mailboxes base. Can add credits to increase.
Both plans support the same mailbox features. Volume caps and API rate limits differ (see choose plan).
Two ways to expand beyond the base
Email-user credits — buy extra mailbox capacity at $1 per mailbox per month, stacking additively on your plan. Best when you need +5 to +50 extra mailboxes. Manageable from Settings → Subscription.
Plan upgrade — Startup → Enterprise gives you +150 mailboxes and doubles the API rate limit. Best when you're consistently near the Startup cap or need Enterprise-only features (dedicated IPs, priority support).
Roughly — under 65 total mailboxes, add credits. Above 65, upgrade.
The pre-warmed pool is separate
Buying a pre-warmed mailbox from the marketplace doesn't reduce your Startup 50 or Enterprise 200 cap. Pre-warmed is billed at $3/address/month and lives in its own counter, separate from your plan's mailbox count.
You can have 50 Startup mailboxes + 100 pre-warmed mailboxes for a total of 150 sending mailboxes, without upgrading your plan.
Domain limits are different
A separate cap. Startup 10 domains, Enterprise 40 domains. Both can be raised up to 500 via Settings → Subscription (self-serve, once per 24 hours).
What's next
Frequently asked questions
What happens when I hit the limit?
The Add Email User button is disabled with a prompt to either buy credits, upgrade, or delete an existing mailbox to free a slot.
Are pre-warmed marketplace mailboxes counted?
No. Pre-warmed mailboxes are a separate pool billed at $3/address/month. They don't count against Startup's 50 or Enterprise's 200 cap.
How much are email-user credits?
$1 per mailbox per month, added on top of your plan. Ideal when you need +5 or +10 mailboxes but a full plan upgrade isn't worth it. Manage from Settings → Subscription.
Do warming mailboxes count against the limit?
Enabling warming doesn't add or subtract from your mailbox limit — warming is a state, not a mailbox count. All 50 (or 200) mailboxes can have warming on.