OPERATIONS / CAPACITY
Usage and limits
Understand email events, storage, recipient and attachment limits, and workspace safety caps.
Loading documentation…
Understand email events, storage, recipient and attachment limits, and workspace safety caps.
Loading documentation…
Each workspace is $12/year—the equivalent of $1/month, billed annually—and includes 1,000 email events each month. Creating an account does not start a subscription; every customer must explicitly choose a paid plan before any charge can occur.
Additional capacity is not currently available through self-service billing. Storage, mailbox, domain, and organization-seat allowances are not sold as capacity packs and should not be treated as contractual limits until they are implemented and published here.
Accepted messages remain in the mailbox until a user deletes the thread or the workspace is deleted. A deleted thread stays in trash for 30 days before its stored messages and attachments are removed permanently.
Workspace data can be downloaded as a portable NDJSON export. The export includes message content only when the requesting person can read the mailbox. Attachment files are not embedded in the export. Startup Mail does not currently publish a general storage quota, so do not treat the absence of one as a contractual unlimited-storage promise.
| Limit | Current boundary |
|---|---|
| To recipients | 10 per message |
| CC recipients | 10 per message |
| BCC recipients | 10 per message |
| Subject | 240 characters |
| Plain or HTML body | 250,000 characters each |
| Attachments | 10 per message |
| Single attachment | 5 MB |
| Complete message | 10 MB configured boundary |
New workspaces use conservative daily sending limits. Monthly event limits and daily outbound limits are checked before a message is queued. A request that exceeds a cap returns 429 with a specific error code such as monthly_limit or daily_limit.
Rate limiting can also return 429 when too many send requests arrive in a short window. Use bounded backoff and do not create an uncontrolled retry loop.
Paid workspace access follows the Stripe subscription state. Expired legacy trials and inactive subscriptions cannot send. Incoming mail remains available when outbound sending is paused for delivery-reputation review.