Send email

Resend

Email API for developers that sends and receives email from a verified domain over REST, SMTP or MCP.

Rate limits

API requests: 10 requests per second per team, shared across API keys13
Same on every plan: Upgrading does not change it1
Burst: No burst allowance3
SMTP: Same as the API21
Quota errors: 429 with daily_quota_exceeded or monthly_quota_exceeded13

Other limits

Daily sending limit: Free: 100 a day, resets at midnight UTC; paid plans: none2
Recipients per email: 50 in to14
Cc and bcc recipients: Not published
Recipient counting: Each To, CC or BCC address counts as one email2
Batch size: 100 emails; one invalid email fails the whole request15
Email size: 40 MB including Base64-encoded attachments16
Bounce rate: Under 4% required3
Spam rate: Under 0.08% required3
User-Agent header: Required; requests without it get 40312
Domain verification window: Status becomes failed after 72 hours24

Read from Resend’s own pages on 2026-11-04. Every number links to the page a value came from. For agents, the same facts as markdown: /tools/send-email/resend.md