What this code means
Code 2.0.0 is a general success status: only class 2 is known, with no more specific status. It is not a message rejection.
Technical meaning
The X.0.0 pattern is the only undefined status code and is used when only the result class is known. In the 2.0.0 variant, that result class is success.
Delivery status
This is a success status, not a temporary or permanent error. If a system shows it as a bounce or rejection, inspect the event classification.
- Class
- Success
- Retry
- Do not retry unchanged
- Suppression
- Check the full context
Retry decision
Do not retry based on code 2.0.0 alone because it belongs to the success class. Retrying could create a duplicate.
Suppression decision
Do not add the address to a suppression list based on code 2.0.0 alone. Make that decision only after checking the context and other independent delivery or rejection events.
Common causes
- The receiving server returned a general success status without a more specific enhanced code.
- The response-processing system retained only the success class or incorrectly routed it into a rejection-handling flow.
Diagnostic steps
- Inspect the raw SMTP transaction response and confirm that it contains the exact enhanced code 2.0.0.
- Confirm that the basic SMTP reply is in the 2xx class and agrees with the enhanced 2.x.x class.
- Trace response mapping in logs and webhooks to determine whether status detail was lost or a successful result was classified as a bounce.
Actions by owner
Sender administrator
- Treat 2.0.0 as a successful result, remove it from retry queues, and do not create a suppression solely from this code.
- If the code entered rejection handling, fix the event parser or mapping and retain the raw SMTP response for audit.
Provider
- Retain the full raw SMTP response and a more specific status code when one is available.
- Review normalization rules when the general 2.0.0 code replaces an available, more specific success status.
Sources and verification
The meaning and class assignment were verified against the IANA registry and RFC 2034, RFC 3463, and RFC 5248. Retry and suppression recommendations, diagnostic steps, and owner-specific actions are separate operational guidance, not standards facts or documented provider practice.
- iana-smtp-enhanced-status-codesT0 source
Enumerated Status Codes / X.0.0
- rfc5248T0 source
Section 2.1: registry fields and non-exclusive Associated Basic Status Code
- rfc2034T0 source
Section 4: enhanced status class agrees with SMTP reply class
- rfc3463T0 source
IANA registry reference for X.0.0
Last verified:
