Reference
Remy Reference/agent/EmailMessageStatus
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EmailMessageStatus

Type
The status a message can hold, from suppressed and failed through delivered and bounced.

Where a message got to. suppressed and failed never reached the provider; sent and delivered did; blocked was dropped by the platform-wide suppression list, usually from a hard bounce recorded for another app, and does not count against your bounce rate.

EmailMessageStatus.ts
type EmailMessageStatus =
  | 'suppressed'
  | 'failed'
  | 'sent'
  | 'delivered'
  | 'blocked'
  | 'bounced'
  | 'complained'
  | 'delayed'
  | 'rejected'