Common Delivery Issues and How to Fix Them
4 min readLast updated: February 20, 2026Shipping & Tracking
problemserrorsreturnsaddress quality
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Even with automated letter delivery, occasional issues can arise. The most common causes are invalid addresses, technical errors during processing, or undeliverable mailings. This article helps you identify and resolve typical delivery problems.
Most delivery issues can be traced back to address quality. Careful maintenance of your customer data is the best way to prevent problems in the first place.
Letters may not be delivered and come back as returns for various reasons:
What you can do:
Returns do not incur additional costs. However, the original delivery costs for the letter are not refunded. The letter was printed and sent -- the costs are incurred regardless of whether the letter could be delivered.
If a noticeably high proportion of your letters come back as returns, the problem usually lies in data quality:
Possible causes:
Solutions:
Status 99 means that DHL could not process the letter. A processing error can have various causes:
What you can do:
Open the letter details in the campaign view. For a processing error, AutoLetter displays the detailed error message from DHL. This message gives you a specific clue about the cause.
Correct the problem based on the error message. Often, it is sufficient to correct the address data of the affected customer or adjust the letter template.
After the correction, the affected recipient will be reconsidered in the next processing round of the campaign, provided they still meet the filter criteria.
If a letter reached the status "Print Center Processing" (meaning it was printed and sent) but the recipient did not receive it:
To minimize delivery issues, we recommend the following measures: