Skip to content

Automatic Retry Policy

Temporary delivery failures use one 24-hour retry policy:

  • Total attempts: 7 (the initial attempt plus 6 retries)
  • SMTP 4xx replies: Deferred and retried; they are not hard bounces
  • Permanent recipient 5xx replies: Hard bounced without retry
  • SMTP command/protocol 500-504 replies: Retried as infrastructure failures
  • Network and timeout failures: Retried

Elapsed Retry Schedule After the Initial Attempt:

  1. Approximately 1 minute
  2. Approximately 15 minutes
  3. Approximately 1 hour
  4. Approximately 4 hours
  5. Approximately 12 hours
  6. Approximately 24 hours

Each temporary attempt records a deferred event and its next retry time. After all attempts are exhausted, the email becomes failed, its next retry time is cleared, a terminal failed event is recorded, and subscribed endpoints receive an email.failed webhook. Pre-send suppression blocks record a suppressed event and can emit the email.suppressed webhook.