TL;DR
Generic success status when only class 2 is known. Treat it as acceptance, not rejection: misclassifying it as a bounce breaks deliverability reporting. This is not a failure; do not retry, and list hygiene is unaffected unless your system wrongly routes it to bounce handling.
What this code means
Registry pattern X.0.0 lands in success class 2 when the reporting system knew the outcome class but could not attach a more specific subject detail. The first digit 2 places the status in the success family of the enhanced status register, so it marks acceptance rather than temporary or permanent delivery failure. The undefined middle and detail positions (.0.0) deliberately carry no finer mailbox, system, or protocol cause. The code alone does not prove final inbox placement, routing path, or that no later event will follow for the same message.
Technical meaning
X.0.0 is the sole undefined status pattern and applies 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
These sources define what this enhanced status code means, mainly through the IANA registry and related RFCs. When provider examples appear on the page, they come from that provider's published documentation. Follow the links to read the original wording in context.
- SMTP Enhanced Status Codes — IANA registry of enhanced mail system status codes.
- RFC 5248 — A Registry for SMTP Enhanced Mail System Status Codes — Creates and governs the IANA enhanced status code registry.
- RFC 2034 — SMTP Service Extension for Returning Enhanced Error Codes — Defines how SMTP returns enhanced status codes to clients.
- RFC 3463 — Enhanced Mail System Status Codes — Defines the class/subject/detail model for enhanced status codes.
Last verified:
