Letter ID
Process and track letters easily

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 Letter ID is is a dynamic, postal data matrix code used to uniquely identify consignments, or as a supplement to franking on the letter.

  • Track the sorting of consignments on both the outward and return journeys
  • Digitized and automated processing of returns
  • Use more advertising space on consignments
  • Customize the content of the Letter ID with information such as the customer number
  • Check completeness of printing or identify letter content



Letter ID – Helsana

Monitoring letter mail and absolute transparency – Helsana has returns management completely under control.

Letter ID – Migros Bank

Managing returns with Letter ID – Migros Bank: Seamless, secure and flexible.

Letter ID – SECO

Simplicity and security with Letter ID – At SECO, there is plenty going on in returns management.

Letter ID – Sunrise

Categorizing returns with Letter ID – Sunrise implements an essential tool for targeted further processing.

Who is this service for?

Letter ID is a service for business customers who maintain a billing relationship with Swiss Post.

Service providers from the printing industry make their range of offers stand apart from the competition using Letter ID and support their customers in optimizing processes and making cost savings.


Digital returns information
Digitization of returns or receipt of digital returns information


0.09 CHF/returns

Qualified disposal of returns
“Qualified disposal” or shredding or returns including their sensitive content


0.02 CHF / returns

All prices in CHF

Prices for returns including VAT

For more information about returns services, please visit www.swisspost.ch/returns.

Here’s how it works


Create a letter consignment with a postage paid impression and the “Letter ID” data matrix code.


Have the data matrix code approved by the Swiss Post final proof team as per the applicable provisions.


Post the PP-franked letter mail and declare them with the order number contained in the data matrix code.


Track the sorting of the letters on the outbound journey.


Receive information about the letters on the return journey.

Sorting information on the outward journey

You can track the sorting results of your Letter ID consignments using the Swiss Post Customer Login for the “Track consignments Business” online service > “Advanced search” > “Letters with Letter ID”. You can also set up active notification via e-mail.

Returns information on the return journey

If you have selected “with data” for the processing of your returns with Letter ID, you can download this using your Swiss Post Customer Login in the “Track & Trace Business” online service, under > “Advanced search” > Download “Returned letters”.


You can create the data matrix codes for Letter ID and Letter ID light in the “Create postage paid impressions” online service.

To create the dynamic Letter ID you need to import your recipient addresses. We will generate the appropriate data matrix code for them. The maximum number of data matrix codes that can be created per address upload is 10 000. 

If you are planning bigger mailings, it may be worth contacting a print service provider/letter shop, or creating the data matrix codes with your own software.

You can choose from the following options: 

  • Digitization
  • Disposal (simple and/or qualified) 
  • Redirect mail 

Letter ID (dynamic code)

  • Uniqueness − each consignment has an individual data matrix code.
  • The production process should ideally use software since each consignment has its own code. Possibility of producing smaller volumes (10,000 addresses per dispatch) within the “Create postage paid impressions” online service.
  • Alphanumeric digits may be used freely in the code by the customer.
  • Individual information on returns and automated further processing possible.

Letter ID light (static code)

  • The data matrix only needs to be created once. This can be done with ease using the “Create postage paid impressions” online service.
  • No individual information on returns except if the individual images of the return shipments are viewed. In this case, an individual conclusion can also be drawn.
  • Address maintenance via DataTransfer is not possible.

Send a data matrix code along with the letter layout to one of our “Final proof” Competence Centers in your region.

Verification is free and you will receive a written response within 72 hours. 

With the dynamic Letter ID, it is beneficial if you submit five copies for homologation to enable the dynamic filling-in process to be simulated. This is not necessary with Letter ID light since the filling-in process is always the same.

To post PP-franked consignments using Letter ID or Letter ID light, you use a dispatch list, which is simply a delivery note. 

For consignments using Letter ID light, simply enter “postage paid impression” as the “Dispatch type”. For consignments using Letter ID, by contrast, record the consignments using “postage paid impression with Letter ID” as the dispatch type and enter the order number integrated into the data matrix code Letter ID.

Set up the electronic “DataTransfer” interface.


Give us a call

CHF 0.08/min. from landline phones within Switzerland
Monday till Friday: 7.30am - 6pm

+41 58 667 85 91

+41 58 667 85 91

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Our address

Post CH Ltd
Post Net
Sales SME
Wankdorfallee 4
3030 Bern