This blog post provides information about email bounces in SAP Marketing Cloud when the service E-mail 365 from Sinch is used as the Email Service Provider (ESP).

Bounces: definition and standards

A bounce occurs when an email cannot be delivered.

The codes for bounces are returned by the ISP and should follow a standard denomination. For example, you can refer to:

https://en.wikipedia.org/wiki/List_of_SMTP_server_return_codes and Simple Mail Transfer Protocol (SMTP) Enhanced Status Codes Registry (iana.org).

Sinch is in general aligned with those, however, some differ. For more information on the Sinch bounce classification, see E-mail 365 – Bounce Classification – Sinch Community – 3532.

Facts about bounces

A bounce code has 3 main parts. For example, let’s review this bounce:

• BOUNCED-FINISHED-HARD_BOUNCE:delivery attempt failed bounced (host ef20.xyz.com[123.4.56.78] said: 552 5.2.2 mailbox quota exceeded for this recipient <abc-company@xyz.com> (in reply to RCPT TO command)), relay: ef20.xyz.com [123.4.56.78]:20111

The 3 mains parts are:

• A SMTP code, here 552
• A sub-code, here 5.2.2
• A language dependent text, here mailbox quota exceeded for this recipient

In addition:

• The SMTP codes follow industry standard. The sub-codes are NOT.

• The bounces are generated by the Internet Service Providers (ISPs). Each ISP can interpret those as they want:
  • New sub-codes are constantly being created with new texts.
  • Texts are language dependent. French ISP Orange, for example, sends French texts.

• This bounce is within the 550-range, which is normally classified as HARD bounce. However, by evaluating the sub-code and the text, Sinch has re-classified this one as a SOFT bounce. The Hard and Soft Bounce assignments can be found within the “statusText” field of the bounce record. While Sinch is regularly updating the classification, it is a challenge to keep up with all the ISPs frequent changes and the fact that the text is language dependent.

SAP Marketing Cloud behavior with bounces

Data quality is key with email marketing and it is part of the best practices to keep the data up-to-date by maintaining it and cleaning it up.

In SAP Marketing Cloud, when a hard bounce occurs, the email address from the contact, is considered as invalid and no longer visible. Sending repeatedly to a hard bounce email address damages the reputation of the sending IP and ultimately can be blocked. The email can be re-activated again if an interaction for this contact and email ID is uploaded.

When a soft bounce occurs, an email address could be added to a suppression list, based on the bounce reason. The function of the suppression list is to avoid a recurring sending to a mailbox user that has bounced. This helps to avoid impact to the IP reputation. Depending on the reason, the email address is removed from the suppression list after a specific period. Refer to the Suppression Lists table from the Sinch E-Mail 365 – Deliverability Best Practices Guide for details.

In SAP Marketing Cloud, when an address is on a suppression list, the interaction created for this bounce is of type ‘DELIVERY_FAILED’ with the reason ‘SUPPRESSED’. To avoid sending emails to contacts for which the email addresses are on the suppression list, there are a few options. For example:

• Remove those contacts from campaigns using the filter mechanism. For more information on filtering in campaigns, see our online documentation Filtering – SAP Help Portal.

• Build a target group that:
  • Filters out those contacts.
  • Selects those contacts if the suppression period has passed, and you want to contact them specifically.

Using the Segmentation Building Blocks, you can create dedicated segmentation filters that can be reused in multiple segmentation models. It allows to have consistency across your segmentation but also save time on recreating segmentation models. For more information, see our online documentation Segmentation Building Blocks – SAP Help Portal

Also, note that SAP Marketing Cloud offers different features to build the email content, like reusable blocks or conditions, which can help to build personalized content that makes it easier to target the different contacts. For more information, see our online documentation Creating and Using Reusable Blocks – SAP Help Portal and Using Conditions in Messages – SAP Help Portal.

Bounces and other supported ESPs

SAP Marketing Cloud also offers an integration with Amazon Web Service – Simple Email Service (AWS SES). Amazon doesn’t publish a clear classification list. However, they have the following document Understand Soft Bounces on Amazon SES.

SAP Marketing Cloud offers as well as an integration with any ESP through a generic interface. Refer to the selected ESP classification for details on how it manages bounces.

Conclusion

The main takeaways are:

• Bounces codes are returned by the ISPs and they are always changing.
• Not all ESPs provide clear classification. Sinch E-mail 365 publishes one of the most detailed lists.
• Hard bounces, which are received from the ISP, impact the sender reputation. Too many hard bounces can lead to the blocking of the sending account.
• Contact data quality is key for strong deliverability and bounces should be actively monitored.

For information on monitoring bounces and removing domain from a SPAM list, see this blog post SAP Marketing Cloud: Email Bounce Monitoring Best Practices | SAP Blogs.

For more information on bounces with SAP Marketing Cloud, see our online documentation Handling Bounces – SAP Help Portal.

SAP Marketing Cloud also delivers analytics stories on bounces. See our online documentation:

Analytics Story: Hard Bounce Detail – SAP Help Portal

Analytics Story: Soft Bounce Detail – SAP Help Portal and Analytics Story: Bounce Statistics – SAP Help Portal.