2.x.x — SMTP Success Codes

Class 2 enhanced status codes report that a server accepted the action they describe. Read the exact code with the full SMTP response or DSN before treating it as a final delivery or recipient-state decision.

A leading 2 means the server accepted the action it describes. Read it with the complete SMTP response or DSN: a success line inside an asynchronous report can still accompany a later problem.

A leading 2 records success for the specific SMTP action or status-report line, not a universal guarantee about the whole mail journey. The detailed code identifies the subject area, while the surrounding event, message identifier, and later delivery reports establish whether a message reached the intended destination or encountered a subsequent problem.

Choose the next check

Read the complete delivery eventCorrelate the class-2 line with the message identifier, timestamp, receiving system, and any later DSN entries before changing recipient state or reporting final delivery.
Check an address-validation resultA success response can confirm the action a server accepted for an address without independently proving later mailbox delivery.
Check mail-system processing resultsUse the exact mail-system code to understand whether the server reports an ordinary successful action or a changed processing attribute.
Check protocol, conversion, or security contextA success-class code can still record a protocol condition, data conversion, or security-related outcome that merits follow-up in the wider event flow.

Common mistakes

Treating any class-2 line as proof that the intended recipient saw the message in the inbox.
Using a success code seen inside a DSN or webhook flow to overwrite later failure evidence for the same message.
Ignoring a detailed success code that reports a conversion or processing change relevant to the application.

Open the exact class-2 code and correlate it with the complete delivery event before recording delivery, retrying a later failure, or changing a recipient's status.