Bounce management: hard vs soft bounce

Bounce Management: Hard Bounce vs. Soft Bounce

In email marketing, especially when working with cold outreach and lead generation, it is crucial to understand how to handle bounced emails (bounces). Improper handling of bounce rate can negatively impact your sender reputation and lead to your mailings being blocked by major email providers such as Gmail, Outlook, or Yahoo.

Postigo automatically handles bounces to protect your reputation and ensure maximum deliverability of your emails. In this article, we will explore the difference between hard bounce and soft bounce, and how Postigo manages them.

Hard Bounce: Permanent Error

A hard bounce means that the email cannot be delivered due to a reason that is unlikely to be fixed in the future. The most common causes of hard bounces are:

• Non-existent email address: The email address does not exist or has been deleted.
• Invalid domain: The domain name specified in the email address does not exist.

The SMTP server typically returns error codes 550 or 553 for a hard bounce. For example:

550 5.1.1 The email account that you tried to reach does not exist.

Postigo Actions: Upon receiving a hard bounce, Postigo automatically adds the email address to the suppression list. This means that no more emails will be sent to this address. Removing hard bounces from your database is a critical step in maintaining its cleanliness and improving sender reputation. A high hard bounce rate (over 2-3%) can seriously damage your reputation and lead to deliverability issues. Regularly cleaning your database of invalid addresses is key to a successful email campaign. You can learn more about maintaining database cleanliness in the article on spam protection.

Soft Bounce: Temporary Issue

A soft bounce means that the email cannot be delivered at the moment, but the issue may be temporary and resolved in the future. The most common causes of soft bounces are:

• Recipient's mailbox is full: The recipient has no space for new emails.
• Temporary server issues: The recipient's server is temporarily unavailable.
• Email is too large: The email size exceeds the limit set by the recipient's mail server.
• Email blocked: The email was blocked by filters on the recipient's side (e.g., due to content or sender reputation).

The SMTP server typically returns error codes 421, 450, or 451 for a soft bounce. Examples:

421 4.4.2 Connection timed out

450 4.7.1 Greylisting in action, please try again later

Postigo Actions: Postigo automatically attempts to resend emails that received a soft bounce within a certain period of time. The number of attempts and the interval between them depend on the system configuration and the recommendations of the SMTP provider. If the email still cannot be delivered after several attempts, the address may be temporarily excluded from the mailing list, but it is not added to the suppression list permanently. It is important to note that a high soft bounce rate (over 5-7%) can also negatively impact your reputation, so it is important to monitor this metric and take steps to reduce it. For example, make sure your emails are not too large and that you are using the correct SPF, DKIM, and DMARC settings to authenticate your emails.

How to Read Bounce Reason

Understanding the bounce reason is critical for diagnosing deliverability issues. The bounce reason is usually contained in the error message returned by the SMTP server. However, these messages are often technical and difficult to understand.

Postigo tries to simplify this process by providing clearer explanations of the bounce reasons in campaign analytics. Nevertheless, here are a few tips for interpreting bounce reasons:

• Look for error codes: As mentioned above, error codes (e.g., 550, 421) provide a general idea of the problem.
• Analyze the message text: Carefully read the text of the error message. It may contain more detailed information about the reason for the bounce. For example, the message "User unknown" indicates that the email address does not exist.
• Pay attention to the domain: Sometimes the error message may indicate problems with the recipient's domain. For example, "Domain not found" means that the domain name does not exist or cannot be resolved by the DNS server.
• Use online tools: There are online tools that can help you interpret complex SMTP error messages.

If you cannot understand the reasons for the bounce, contact Postigo support. We will help you diagnose the problem and find a solution.

Conclusion

Proper bounce management is an important part of a successful email marketing strategy. Understanding the difference between hard bounce and soft bounce, as well as knowing how Postigo handles them, will help you maintain the cleanliness of your database, improve your sender reputation, and increase the deliverability of your emails. Regularly analyze the bounce rate of your campaigns and take steps to reduce it. Use the capabilities of AI content rotation and spintax to avoid being caught in spam filters. Remember that a clean database and a good sender reputation are the key to a successful email campaign.