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Usage and quotas

Settings → Billing → Usage shows live counts vs. your plan limits.

Accounts (the only count-based quota)

Counts every connected mailbox and every custom domain attached to your workspace. A “mailbox” here means one Gmail / Workspace address, one Outlook / M365 mailbox, one Yahoo mailbox, or one IMAP/SMTP account. Aliases and send-as addresses on an existing mailbox do not count as separate accounts.

PlanLimit
Starter2
Plus3
Pro6
Business11

You can use these slots however you want - any mix of personal mailboxes and custom domains. Examples for Plus (3 slots):

  • 3 Gmail accounts, 0 custom domains.
  • 2 Gmail + 1 custom domain.
  • 1 Gmail + 1 Yahoo + 1 custom domain.
  • 3 custom domains, 0 personal mailboxes.

Custom domains count for 90 days after you deactivate them (in case you want to reactivate). Fully-removed domains don’t count. Going over the limit blocks connecting new accounts or adding new domains; everything already connected continues syncing.

Storage

Total size of message bodies + attachments stored in your workspace. Growth is usually slow (~100-500 MB per month for heavy email users).

PlanLimit
Starter10 GB
Plus25 GB
Pro75 GB
Business200 GB

If you exceed storage:

  1. We send warning emails at 80% and 95%.
  2. At 100% we stop syncing new inbound attachments (metadata + body still sync).
  3. At 110% we stop syncing new inbound entirely.

Sending stays unblocked at all levels.

Reducing storage

  • Settings → Billing → Storage usage shows a per-account breakdown and a “Largest attachments” list.
  • Delete large attachments or forwarded newsletters from an affected account.
  • Emptying Trash is a fast way to reclaim 5-20% on most workspaces.
  • Reduce the per-account backfill window in Settings → Accounts → [account] → Sync range.

Outbound send limits

There is no fixed per-day or per-second send cap on outbound mail today. Sending is gated by reputation: SuperMail tracks bounce and complaint rates per sender (via SES feedback loops) and pauses outbound for an account that crosses a threshold over a rolling window. As long as your bounce / complaint rate stays low, you can send freely.

If you need to send a newsletter or marketing campaign, use a dedicated ESP - SuperMail isn’t intended for bulk marketing sends, and a campaign will trip the reputation guard fast.