C4 Rigid Mail

Mailingsystem for hardcover envelopes

With the C4 Rigid Mail, we offer an adaptable and variable machine solution for the processing of mailings with hardcover envelopes at a speed of up to 4000 envelopes per hour.




Enclosure Station




Final Processing

Short description

The highest product security meets maximum flexibility

The C4 Rigid Mail system allows hardcover envelopes to be selectively filled, and to be prepared intelligently for their dispatch with various processing options. These envelopes can be made from different materials in order to guarantee the highest product protection during its transportation.



  • Formats C5 (162 x 229 mm); B5 (176 x 250 mm), C4 (229 x 324 mm); B4 (250 x 353 mm)
  • Different materials (e.g., hard cover, padded, paper, etc.)
  • Also: complete card mailings


  • Format from min 80 x 150 mm to max. 235 x 330 mm
  • Up to 8 enclosures possible, also stapled
  • Strength of insertion: up to 9 mm, min 60 g/m²

Final products

Hardcover envelopes with inserted mailings and selective enclosures


In the feeding process, closed envelopes, covering letters or other documents, are isolated for onward processing and later enveloped. Furthermore, they can be read and verified. These products can be printed inline or they may be already pre-personalised. Also a complete card canal can be integrated at this point into the system..

Enclosure station

Insurance policies, trading terms and conditions, receipts, advertising flyers and other enclosures can be added selectively to the remaining documents in the insertion station. Variable possibilities regarding the choice of insertions, supported by a comparison with input data in the database, permit a flexible and purposeful optimisation of this process. Thus personalised or non-personalised insertions can be combined as desired and be put together intelligently.


During the inserting procedure, the accumulated documents are inserted into the hardcover envelopes which are then closed by means of cold glue.

Final processing

In the final processing, variable possibilities for intelligent subsequent treatment are available. After the application of an address label, various control mechanisms ensure that only flawless envelopes are transported to the next conveyor belts. These controlling options range from an integrated weighing scales, to cameras or sensors that check the measurements of the filled and closed envelopes. In the last step of the post-processing, the finished envelope can be sorted or grouped according to agreed factors such as, for example, their weight, postal code, receiver’s branch, country of destination, or for special delivery by courier service. Optical aids like coloured markings, or dividing labels, make the collected groups on the conveyor belt recognizable.

Special features

  • Selective insertion and treatment of mailings
  • Innovative quality inspections to avoid false dispatch
  • Fully automatic enveloping at the highest security level

Technische Daten

ThroughputUp to 4.000 envelopes/hour
Operators needed1
Envelope formatsC4/C5
Max. insertion thickness16 mm standard (up to 25 mm optional)
Temperature/HumidityOptimal: 20-25°C room temperature, 60 % relative humidity

“Die C4 Rigid Mail creates a new benchmark for intelligent inserting. The reliable system allows easy postage optimization and complete product safety.”

Jens Reichardt, service technician


Do you have any questions? We are happy to talk to you at any time. Write us a message or just call us. We look forward to your inquiry!

Otto Künnecke GmbH
Bülte 1
37603 Holzminden


Fon +49-5531-9300-888