Startup includes 50 mailboxes and Enterprise includes 200. Beyond that, extra mailbox credits cost $1 per mailbox per month. On a paid plan you don't have to buy them in advance: when you add mailboxes past your limit, the Add Email User dialog shows the extra cost and adds the credits as part of creating them. You can also manage credits in Settings → Subscription. Pre-warmed marketplace mailboxes ($3 per address per month) are a separate pool and don't use your plan's slots. Separately, each domain usually holds up to 10 mailboxes.
What's included by plan
- Startup ($69/month): 50 mailboxes, 10 domains.
- Enterprise ($189/month): 200 mailboxes, 40 domains.
Both plans have the same mailbox features. See Choose a plan for the full comparison.
Two ways to go beyond the base
Extra mailbox credits: $1 per mailbox per month, added on top of your plan. Added automatically when you create past your limit, or set a number yourself in Settings → Subscription.
Upgrade to Enterprise: 200 mailboxes and 40 domains included, plus a higher API rate limit and access to dedicated IPs.
The break-even is about 170 mailboxes: Startup plus 120 credits costs $189, the same as Enterprise. Below that, credits on Startup are cheaper, unless you also need more domains or Enterprise features.
The pre-warmed pool is separate
Buying pre-warmed mailboxes from the marketplace doesn't reduce your plan's mailbox cap. They're billed at $3 per address per month in their own pool.
So you can run 50 Startup mailboxes plus 100 pre-warmed mailboxes, 150 in total, without upgrading.
Domain limits are separate too
Your plan also has a domain limit (Startup 10, Enterprise 40). You can raise it yourself from Settings. See Increase your domain limit.
What's next
Frequently asked questions
What happens when I hit the limit?
On a paid plan, you can keep adding mailboxes. The review step of the Add Email User dialog shows how many extra credits are needed and the button reads "Create Email Users (+$N/mo)". The credits are added to your subscription when you confirm. If the payment fails, no mailboxes are created.
Are pre-warmed marketplace mailboxes counted?
No. Pre-warmed mailboxes are a separate pool billed at $3 per address per month. They don't count against Startup's 50 or Enterprise's 200, and new mailboxes you add to a pre-warmed domain are billed the same way.
How much are extra mailbox credits?
$1 per mailbox per month, on top of your plan. Manage them in Settings → Subscription.
If I delete mailboxes, do my credits go down?
No. Deleting frees slots, but credits you bought stay on your subscription until you lower them in Settings → Subscription.
Do warming mailboxes count against the limit?
Warming doesn't change your mailbox count; it's a setting on a mailbox you already have. Every mailbox can have warming on, at $0.60 per mailbox per month.
Do external mailboxes I import for warming count?
No. Imported external mailboxes are warming-only and don't use your plan's mailbox slots.
How many mailboxes can one domain have?
Usually up to 10. The Add Email User dialog warns you and won't submit if a domain would go over. Winnr recommends around 5 per domain for cold email.