Soft bounce is an email marketing term used to describe a scenario where an email message is sent out, but is not successfully delivered to the recipient's inbox. It is also known as a soft rejection or deferred email. Soft bounces occur when an email server temporarily rejects an email message, either due to a technical issue or because the email address is invalid.
Unlike hard bounces, which occur when an email message fails to reach its intended recipient due to a permanent issue, soft bounces can often be corrected and the email can be successfully delivered. This makes soft bounces an important part of any email campaign, as they can provide valuable insights into email deliverability, effectiveness and optimization.
A soft bounce is an email which cannot be delivered at the time it is sent, but may be delivered at a later time if the issue causing the soft bounce is resolved. Common issues that can cause soft bounces include a recipient's mailbox being full, the email being too large, a server or protocol timeout, or the server not being able to recognise the recipient email address.
Soft bounces can often be corrected. However, the mechanism for doing this will be dependent on the type of issue causing the problem. For example, if a temporary problem with server or protocol timeout is responsible, the email may be successfully delivered when the server is back up and running. In other cases, the email may be successfully delivered later on if the recipient's mailbox is once again able to accommodate further emails.
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It is important to note that the inbox provider is ultimately responsible for the delivery of emails, and the sending side can only do its best to be compliant and deliver emails in accordance with the rules laid out by the provider.
In some cases, soft bounces may need to be manually investigated as they can often provide useful insights into email deliverability, effectiveness and optimization. For example, they may be caused by an ISP blocking certain content, or certain email domains being blocked. This can provide clues as to what type of content needs to be avoided in order to increase the likelihood of emails being successfully delivered.
When dealing with soft bounces, it is important that the bounces are monitored and responded to accordingly. A sender should keep a record of soft bounces and regularly review them to see if issues can be determined and if so, how to resolve them. When dealing with a particular email address, if the problem causing the soft bounce is not corrected but rather persists, then it is advised to put the sender on a do-not-contact list. This will avoid further soft bounces and allow efforts to be focused on those addresses that are valid and deliverable.
In regards to best practices, it is advisable to periodically review your contact list to ensure it is up-to-date with accurate, valid email addresses. This will help to reduce the chances of soft bounces occurring. It is also advisable to use an email service provider (ESP) to monitor soft bounces and provide insights into delivery issues. In addition, regularly reviewing the content of emails to ensure the correct size, format and subject length can help to reduce soft bounce rates. Finally, it is important to respond to soft bounces promptly and analyse the data to determine what changes can be made in order to improve the efficiency of email campaigns.