Service Level Agreement

1. Definitions

• "Service" means the PostStack API, dashboard, SMTP submission, mailbox IMAP/POP3 access, and webhook delivery infrastructure.
• "Monthly Uptime Percentage" is calculated as (total minutes − downtime minutes) / total minutes × 100, measured in calendar months UTC.
• "Downtime" means a period during which the API returns 5xx responses or fails to accept SMTP submission for at least two consecutive 60-second status snapshots (visible on the public status page).
• "Excluded Downtime" means scheduled maintenance announced at least 48 hours in advance, force majeure, third-party DNS or upstream network failures outside our infrastructure, and customer-caused issues (invalid DNS records, bad API usage, plan limit exhaustion).

2. Availability targets

The following Monthly Uptime Percentages apply per plan:

• Pro: 99.9% (≈ 43.2 minutes of allowed downtime per month)
• Scale: 99.95% (≈ 21.6 minutes per month)
• Enterprise: 99.99% (≈ 4.3 minutes per month) with custom commitments available on request

3. Service credits

If we miss the Monthly Uptime Percentage for your plan in a given calendar month, you may request a service credit. The credit is applied against the following month's invoice.

• 99.0% – 99.9%: 10% of monthly subscription fee
• 95.0% – 98.99%: 25% of monthly subscription fee
• Below 95.0%: 50% of monthly subscription fee

Credits are capped at 50% of the monthly fee and are the sole and exclusive remedy for SLA breaches. To request a credit, email support@poststack.dev within 30 days of the affected month.

4. Support response times

• Pro: First response within 1 business day for support tickets.
• Scale: First response within 4 business hours for support tickets; 1 hour for Severity 1 incidents.
• Enterprise: 24/7 incident response for Severity 1; 1 business day for general inquiries; dedicated Slack channel available on request.

Severity 1 means the Service is completely unavailable for your account or a critical feature is broken with no workaround.

5. Maintenance windows

Routine maintenance is performed during low-traffic windows (typically 02:00 – 04:00 UTC on weekends). We announce planned maintenance at least 48 hours in advance via the status page and via email to billing contacts. Maintenance windows are excluded from uptime calculations.

6. Incident communication

Active incidents are posted to the public status page within 10 minutes of detection. Post-incident reviews for Severity 1 events are published on the status page within 5 business days of resolution.

7. Changes to this SLA

We may update this SLA from time to time. Material changes will be communicated via email to billing contacts at least 30 days before they take effect. The current version is always available at this URL.