We strongly advise that you do an A/B test in the pilot - of course, this increases cost slightly, as two designs or formats are being tested against each other, but provides a very insightful view of the potential for optimisation. 

Warning on Noto Emoji 14.0 Note: The following information only apply to the design itself. Of course, the printing and postal guidelines also have to be followed. To make this as easy as possible, we saved our design guidelines under "optilyz > start > design resources" (Login required - guidelines for mailings within Germany). You can find the international guidelines here.

We will check your designs as soon as the mailing has been booked and will provide feedback if necessary as we want to avoid additional cost in production and during postage.

Content logic and focus

A content check on "who does what for whom when and why" is helpful. A customer should understand what it's all about in 5 seconds.


  • A clear and specific reason for the mailing in the subject line, e.g. “we miss you” shows that the customer has not been mailed randomly and therefore performs better (20 - 50%).
  • The customer needs to be addressed by their name. Much better is a repetition of the name “we miss you, Miss Schmidt” and then “Dear Miss Schmidt”.
  • The name should always appear on both sides on postcards - this way they are more relevant to the customer.


  • Highlight the exclusivity of the incentive with the voucher value: “Your exclusive X€ voucher” or “10% discount exclusively for you”.


  • Images close to the brand and the reason for the mailing convert best. 
  • Mood images perform generally better than product images. 
  • The logo should definitely be included.

1:1 Image personalisation

Voucher codes / Incentive

  • The voucher validity (especially in the pilot) should be approximately 10 weeks long (the channel converts slower than e.g. email, hence we recommend 8 - 12 weeks). 
  • Codes should be either individual or, if the code is generic, it should appear individual - e.g. “DHS36f” instead of “summer2020”. 
  • Instead of “Discount code” rather “Your exclusive discount code” - to highlight exclusivity. 
  • We have seen many A/B/C tests with € voucher vs % voucher vs. free gift and the free gifts always perform a lot lower. 
  • We recommend to print the voucher code in a white box - this way you highlight that the code is individual. 


  • The text should be clean and structured.
  • A shorter text with important paragraphs in bullet points/icons etc. perform best.
  • Based on our data we know that parts of the text highlighted in bold perform best. 
  • Letters with a simple colour design convert significantly better. Less is more! 


  • A (blue) signature e.g. of the GM or Head of Customer Service performs better than “Your Team”.
  • This can also be a fictive person.

Small print

  • The small print is an important place to highlight urgency - e.g. "The voucher is valid until X and is applicable across our whole product range".

→ You can also find more tips for postcards here.

→ You can also find more tips for letters here.