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Bounce Categories

Webhook 

These are the bounce categories which are sent in the webhook response when an email gets bounced.

How do they work?

When an email gets bounced, a webhook response is send to the public API you provided at the time of onboarding. The response contains the bounce category and description.

Bounce CategoryDescription
0Non-bounce: This occurs when the bounce processor receives an email that it cannot classify as a bounce or any other non-bounce code (e.g. 60 - Auto-reply).
10Bad email address: This is a hard bounce where we were able to positively identify that delivery attempts to this email address should no longer be attempted. This usually indicates that the requested mailbox does not exist.
20Temporary failure - General: This is a soft bounce which indicates a possibly temporary failure in delivery of the message. The email address itself may or may not be invalid, often the result of ambiguous messages such as a mailbox being "inactive" or "unavailable".
21Temporary failure - DNS Failure: This is a soft bounce caused by a failed DNS lookup. This can be caused by failures in DNS lookup either by TinyEmail itself or subsequent relay servers.
22Temporary failure - Mailbox full: This is a soft bounce caused by the recipient's mailbox or quota being full.
23Temporary failure - Message too large: This is a soft bounce caused by the destination email server rejecting the message due to its size.
24Temporary failure - Missing MX record: This is a soft bounce caused by the destination email server not having an MX record.
29Temporary failure - Unable to connect: This is a soft bounce where we were unable to connect to the remote server. If there are many bounces with this code for a single domain, this usually means that the domain is not working or that the domain is blocking your mail server.
40General Bounce: This is a soft bounce that could not otherwise be categorized. TinyEmail positively identified that this is a bounce message, but was unable to determine a more specific category.
50Mail block - General: This is a soft bounce caused by the remote server rejecting the message for reasons that are not otherwise covered by a more specific "Mail block" category.
51Mail block - Known Spammer: This is a soft bounce caused by the remote server rejecting the message because it considers the sender to be a spammer. These bounces are not specific to the individual message, but rather the sending server itself. This can be caused by listing on various public or private block lists.
52Mail block - Spam detected: This is a soft bounce caused by the remote server rejecting the individual message content as spam.
53Mail block - Attachment detected: This is a soft bounce caused by the remote server rejecting the individual message due to its inclusion of one or more attachments.
54Mail block - Relay denied: This is a soft bounce caused by the remote server refusing to serve as a relay for delivery of the message.
55Mail block - SPF/DKIM/DMARC: This is a soft bounce caused by the remote server refusing delivery of the message due to SPF, DKIM, or DMARC policies. Resolving the specific complaint in the bounce message can often improve deliverability.
59Mail block - Unable to connect: This is a soft bounce where we were unable to connect to the remote server (much like code 29).
60Auto-reply: These are messages received by the bounce processor that were generated by an auto-reply system such as a vacation autoresponder. These are not actual bounces.
70Transient bounce: This is a soft bounce caused by a temporary delay in message transmission.
90Unsubscribe: This is a hard bounce caused by a request to unsubscribe from the mailing list.
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