EmailBounceReason

Recipient was on suppression list at send time. The original SMTP failure that suppressed it is in 'details' when available.

Recipient is a no-reply address.

Received a permanent delivery failure (e.g. mailbox does not exist).

Receiving server temporarily failed delivery (e.g. greylisting, network issue).

Recipient marked the email as spam.

Recipient's mail server flagged the email as spam.

An auto-responder reply was received from the recipient (e.g. out-of-office).

Recipient domain failed DNS resolution.

Recipient's server returned a soft bounce.

Recipient was undeliverable for an unspecified reason.

Recipient address is malformed or invalid.

Recipient was manually deactivated.

Recipient was blocked by provider.

Bounce reason is not known.