What are bounce message error codes and how should I interpret them?

Email marketer from SendGrid shares that understanding bounce codes helps identify and segment problematic email addresses. Implementing a bounce management system based on these codes is crucial for maintaining sender reputation and improving deliverability.

Email marketer from Reddit explains that you should pay attention to hard bounces (5xx errors) and remove those addresses from your list immediately to avoid damaging your sender reputation. Soft bounces (4xx errors) may be temporary, so you can retry sending to them later.

Email marketer from MailerLite shares that regularly cleaning your email list by removing hard bounces and unengaged subscribers is vital for maintaining a low bounce rate. This improves your sender reputation and increases the likelihood of your emails reaching the inbox.

Email marketer from HubSpot shares that bounce messages provide valuable insights into why emails are not being delivered, helping to identify issues with email addresses, server configurations, or content. Analyzing these messages can help improve email deliverability and engagement.

Email marketer from EmailOctopus explains that hard bounces indicate a permanent issue with the email address, like a typo or nonexistent account, and these addresses should be immediately removed. Soft bounces, however, could be temporary issues like a full inbox or server problem, and you might try sending to them again later.

Email marketer from ActiveCampaign shares insights on how to understand and manage your email bounce rate, suggesting steps such as validating email addresses and properly segmenting your email lists. Managing your bounce rate helps to ensure better deliverability and higher engagement.

Email marketer from Stack Overflow shares a common set of SMTP codes. They share that 550 indicates the mailbox is unavailable and provides a permanent failure. 450 indicates the mailbox is temporarily unavailable.

Email marketer from Email Geeks confirms Steve's advice, sharing that he uses regular expressions to filter bounces into categories and classifies based on text for some ISPs, as one code might mean different things for different ISPs.

Email marketer from Constant Contact explains that there are two main categories of email bounces: soft bounces and hard bounces. Soft bounces are temporary and often due to a full inbox or server issues, while hard bounces are permanent and usually due to an invalid or non-existent email address. Properly handling both types of bounces is critical for maintaining a healthy email list and good sender reputation.

Expert from Email Geeks explains the three parts of a bounce message: the three-digit SMTP code (defined by RFC 5321), the enhanced mail system status code (RFC 3463), and free text created by the ISP. The SMTP code is the most important, and the rest is additional detail. He recommends keeping bounce handling rules as simple as possible, focusing on the three-digit SMTP response code, and adjusting for specific problems. Also shares links to resources with more information.

Expert from Word to the Wise shares that bounce handling is complex because the meaning of specific error codes can vary between ISPs and email service providers. Creating a robust bounce processing system needs flexibility to handle inconsistent bounce codes and messages.

Expert from Word to the Wise explains that there are different types of bounces which are 'hard' (permanent failure) and 'soft' (temporary failure). Hard bounces indicate issues like invalid addresses, while soft bounces indicate issues like full mailboxes or server problems. Understanding these differences is crucial for proper list hygiene.

Expert from Email Geeks mentions that many ISPs sending response codes have not read the RFCs. She also points out that about 50% of bounces do not have extended SMTP codes and some ESPs strip the SMTP response code.

Documentation from RFC 5321 explains that SMTP reply codes are three-digit numbers where the first digit indicates success, error, or incomplete status. Codes starting with 2 indicate success, 4 indicate transient errors (retryable), and 5 indicate permanent errors.

Documentation from Oracle explains that bounce message handling involves parsing the SMTP response codes and messages to determine the reason for the bounce. This allows for automated processes to update subscriber statuses and maintain a clean mailing list.

Documentation from SparkPost explains their classification of bounces into categories like 'invalid_recipient', 'mailbox_full', 'policy', and 'technical'. Each category corresponds to specific SMTP error codes and provides guidance on how to handle them for optimal deliverability.

Documentation from Mailjet explains that bounce codes are standardized responses from mail servers indicating why an email wasn't delivered. Hard bounces indicate permanent reasons (invalid email address), while soft bounces indicate temporary issues (full mailbox).

Documentation from Microsoft Learn explains that Non-Delivery Reports (NDRs) in Exchange Online contain enhanced status codes that provide detailed information about delivery problems. The codes are structured as x.y.z, where x indicates the class of failure, y indicates the subject, and z provides granular error details.