Why are Bounceback Message, SMTP Reply Code, and SMTP Error Code fields blank in bounce reporting?

Blank Bounceback Message, SMTP Reply Code, and SMTP Error Code fields in bounce reporting occur due to several interconnected factors related to how emails are handled and how errors are reported across different systems. These reasons include the type of delivery failure (in-band or out-of-band), whether the platform's processing extracts the relevant information from bounce emails, internal suppression by sending systems based on pre-defined rules, issues from asynchronous bounces (particularly due to elderly autoresponders), and server-side configurations where servers aren't set up to report detailed SMTP codes or hide error messages. Aggressive spam filtering, the absence of proper DNS records, greylisting, auto-replies, and the potential failure of email platforms to correctly parse SMTP responses also add to the problem. In sum, diagnostic codes may be missing because they were never issued or are sometimes skipped by the receiving system.

Blank bounceback messages, SMTP reply codes, and SMTP error code fields in bounce reporting typically arise from various reasons related to the receiving server's configuration, email filtering practices, and asynchronous bounce scenarios. Receiving servers might not always provide detailed error information, especially if they're configured to suppress such details or if the bounce is asynchronous (delayed). Aggressive spam filters, missing or incomplete DNS records, greylisting, or the use of auto-replies can also result in the lack of standard bounce information. Additionally, some email platforms might fail to properly parse or display the SMTP response, or incomplete SMTP responses.

Blank bounceback messages, SMTP reply codes, and SMTP error code fields in bounce reporting can stem from several factors related to how email failures are handled and reported. Delivery failures can be 'in-band' during the SMTP transaction or 'out-of-band' after the message has been accepted. The platform's ability to extract and display information from bounce emails is crucial, but some bounce handlers may not process it well. Sending systems might suppress sending due to internal rules, bypassing the SMTP stage. Missing data fields may indicate asynchronous bounces from autoresponders. Diagnosing the issue requires understanding the source of the data and consulting ESP support. Receiving servers not configured to report detailed codes or set to hide error messages, or simply not issuing the codes in the first place are also key factors. Cleaning up autoresponders is key as well.

Blank SMTP fields in bounce reporting are often caused by a lack of detailed error information from the receiving server, internal filtering processes, or variations in the implementation of SMTP standards. Receiving servers may not provide specific error codes during the SMTP transaction, or the email might not even reach the server due to internal filtering. The actual level of detail available in bounce messages also depends on the sending server's configuration and interactions with other servers. The 'Undetermined' status code from AWS, further contributes to a lack of clarity.