Two plans. Same product.

• REST API and SMTP relay
• No limit on sending domains
• SPF, DKIM and return-path verification
• Open and click tracking, per domain
• Webhooks with automatic retries
• Inbound email delivered to your webhook
• Suppression list and one-click unsubscribe
• Test-mode API keys and a sandbox inbox
• Email data processed and stored in the EU

Per-minute limit over HTTP. The response carries a Retry-After header.

429 rate_limited

Monthly quota used up. No Retry-After: a short wait does not fix a used-up month. The quota resets on the 1st at 00:00 UTC.

429 quota_exceeded

Either limit over SMTP. A temporary reply, so your mail software retries on its own.

452

The per-minute limit counts sends: one HTTP send request or one SMTP message. The monthly quota counts emails: every recipient a send is delivered to uses one, and a recipient dropped for being suppressed does not. An HTTP send takes up to 50 addresses in each of to, cc and bcc; an SMTP message takes up to 50 recipients in total. A rejected send is never queued by zSender. The error slugs are listed in the docs.

Prices are in USD. Pro is $29 a month, or $290 a year, two months free at the yearly price. Payments run through Polar, our merchant of record, which handles the charge, invoicing and tax.

Free needs no card. To cancel Pro, use Cancel subscription on the Subscription card in Settings: your plan stays Pro until the end of the current billing period, then moves to Free.

• GDPR-Compliant, EU-Hosted Email API/gdpr-email-api
• zSender vs SendGrid/compare/sendgrid
• zSender vs Resend/compare/resend
• zSender vs Mailgun/compare/mailgun
• zSender vs Postmark/compare/postmark
• Tools/tools
• SPF checker/tools/spf-checker
• DKIM checker/tools/dkim-checker
• DMARC checker/tools/dmarc-checker
• Quickstart: send your first email/docs/quickstart