Mailbox providers generally do not publish detailed bounce message explanations due to a combination of factors. A primary concern is preventing spammers from exploiting detailed information to bypass filters and improve their techniques. The complexity and variability of bounce messages, coupled with the constantly changing email landscape, makes maintaining accurate and up-to-date documentation challenging. Many experts believe that existing resources, such as SMTP RFCs and postmaster pages, often provide sufficient information if senders are properly trained to interpret them. Additionally, some providers intentionally maintain a degree of ambiguity for security reasons or because the technical specifics are implementation-dependent. The lack of detailed explanations also stems from resource constraints within postmaster teams and a perception that the effort required to create and maintain such documentation would not be an effective use of their time, especially when senders often fail to interpret the existing information correctly or seek help even when the answer is readily available in the bounce message itself.

Mailbox providers generally do not publish detailed bounce message explanations primarily to prevent spammers from exploiting this information to bypass filters and improve their techniques. The complexity and variability of bounce messages, coupled with the constantly changing email landscape, makes maintaining accurate and up-to-date documentation challenging. Additionally, providers often believe that the current bounce messages are sufficient for those who understand how to interpret them, and that increased clarity would only benefit malicious actors.

Experts suggest that mailbox providers don't publish detailed bounce message explanations for several reasons. Existing SMTP response codes and postmaster pages often provide sufficient information, but senders may lack the training to interpret them correctly. Prioritizing clear communication is also resource-intensive for postmaster teams already stretched thin. Moreover, publishing detailed explanations could inadvertently aid spammers in bypassing filters. Sometimes providers are vague on purpose and the problem often lies in the readers ability to understand the explanations as is.

Documentation suggests that mailbox providers do not publish detailed bounce message explanations for a combination of reasons. SMTP reply codes, as defined in RFC 5321, are intended to provide a general outcome rather than specific details due to the wide variability and implementation-specific nature of failures. Additionally, providers like Google and Microsoft obscure full reason codes to protect against spam and abuse, prioritizing the prevention of insight for malicious actors. The technical and frequently changing nature of these specifics also contributes to a lack of detailed, publicly available documentation.