Sandbox and limits
The sandbox, production access, plans, quotas and other sending limits.
Before you can send
An organization can send email when:
- At least one member has verified their email address (from the link sent at sign-up). Otherwise every send fails with
403 forbidden. - The sender address is on a verified domain. See Verify a domain.
- The organization is not suspended.
Sandbox
Every new organization starts in the sandbox on the Free plan. In the sandbox:
- You can send only to verified members of your organization. Every recipient in
to,ccandbccmust be one. Other recipients fail the whole request:
{
"statusCode": 403,
"name": "forbidden",
"message": "In sandbox mode, you can only send to verified members of your organization ([email protected] is not one). Request production access to send to any recipient."
}- You cannot send broadcasts.
- The Free plan quotas apply: 100 emails a day and 3,000 a month.
To test with teammates, add them as members of your organization under Settings. Once they verify their email address, you can send to them.
Production access
To send to anyone, request production access from the banner in the dashboard. Tell us your website, what kind of email you send and the volume you expect. The usend team reviews each request to protect the deliverability of everyone sending through usend, and emails the organization's owners with the decision.
Paying for a plan does not lift the sandbox by itself: production access is a separate approval.
Plans and quotas
| Plan | Monthly emails | Daily emails | Broadcasts | Data retention |
|---|---|---|---|---|
| Free | 3,000 | 100 | No | 3 days |
| Pro | 50,000 | No daily limit | Yes | 30 days |
| Scale | 200,000 | No daily limit | Yes | 90 days |
Plans and payment are managed under Billing in the dashboard. The quotas that apply to your organization are shown there; the usend team can set different limits for an organization.
How quotas are counted:
- Each email counts once, whatever its number of recipients. A batch of 100 emails counts as 100.
- Broadcast emails count too. A broadcast is checked against your remaining quota for the whole audience before it starts.
- Days are counted in UTC. The monthly quota resets on the first day of each calendar month (UTC).
When a send would exceed a quota, it fails with 429:
| Name | Meaning |
|---|---|
daily_quota_exceeded | You have reached your daily quota. |
monthly_quota_exceeded | You have reached your monthly quota. |
Rate limit
The API accepts up to 10 requests per second per API key. See Rate limits.
Message limits
| Limit | Value |
|---|---|
Recipients per email (to + cc + bcc) | 50 |
| Emails per batch request | 100 |
| Attachments per email (decoded, total) | 40 MB |
| Request body | 50 MB |
| Scheduling | Up to 30 days ahead |
| Tag name or value | 256 characters |
Data retention
usend keeps email content for your plan's retention period (see the table above). After that, the HTML and text bodies of sent emails, their attachments, and received emails with their attachments are deleted. Sent emails stay listed with their metadata and status. Email events are kept for 90 days, and webhook delivery logs for 30 days.
Suspension
usend can suspend an organization, for example for abuse or when bounce or complaint rates get too high (see Bounces and suppressions). A suspended organization cannot send: requests fail with 403 forbidden and include the reason, and emails that are still queued fail.