Dialogpost Requirements: What You Need for Bulk Mail in Germany

Dialogpost is the most cost-effective mailing product offered by Deutsche Post for advertising mailings, customer magazines and catalogues in Germany. The postage is a fraction of standard letter rates. The catch: Deutsche Post enforces a set of strict requirements before accepting a mailing as Dialogpost. Miss a single specification and you may end up paying full standard postage – or having your entire batch rejected.

This article covers all the requirements you need to know in 2026: from minimum quantities and format specifications to addressing rules and data quality. Particularly on the data preparation side, many campaigns fail before the first letter even leaves the building.

Minimum Quantities and Submission Rules

Dialogpost is designed for mass mailings. Deutsche Post therefore requires a minimum volume per submission:

• At least 1,000 items per submission (identical advertising content)
• All items must be content-identical, differing only in personalised elements (name, address, individual offers)
• Submission must be bundled at a single location

Below the 1,000-item threshold, Deutsche Post will not accept Dialogpost. For smaller volumes, standard letters or Infopost (from 50 items) remain as alternatives.

Partial Submissions and Splitting

When sending to multiple regions, the mailing can be submitted at different mail centres. In this case, each partial submission must still meet the minimum quantity. The exact thresholds depend on your contract with Deutsche Post.

Submission Type	Minimum Quantity	Requirement
Single submission	1,000 items	One location, one date
Partial submission	Per contract	Multiple mail centres possible
Consolidated via lettershop	1,000 items total	Lettershop bundles for you

For companies that regularly send fewer than 1,000 items, working with a lettershop that consolidates mailings from multiple clients is a practical solution.

Format Specifications: Size, Weight and Material

Deutsche Post distinguishes three Dialogpost formats. Each has its own size and weight limits:

Standard Letter (Dialogpost Standard)

• Minimum size: 140 × 90 mm
• Maximum size: 235 × 125 × 5 mm
• Weight: up to 20 g (compact letter up to 50 g)
• Shape: rectangular, no unusual shapes
• Material: machine-compatible (not too thick or rigid)

Large Letter (Dialogpost Groß)

• Minimum size: 100 × 70 mm
• Maximum size: 353 × 250 × 20 mm
• Weight: up to 500 g
• Shape: rectangular or in approved foil wrapping

Postcard

• Dimensions: 140 × 90 mm to 235 × 125 mm
• Paper weight: at least 150 g/m² (stable enough for machine processing)
• Weight: up to 20 g

A common mistake: items that exceed the maximum dimensions by even a few millimetres are automatically reclassified into the next (more expensive) category – or rejected entirely. Measure your samples before production.

Addressing and Franking

Addressing is one of the most critical points. Deutsche Post sets strict requirements for machine readability:

Address Field Position

The address field must be placed in a defined area:

• Franking zone (top right): 74 × 40 mm, free of graphics and text
• Reading/coding zone (bottom): 15 mm from the lower edge, free of graphics
• Address field: At least 40 × 25 mm, machine-readable font

Font and Readability

CORRECT:
  Herr Max Müller
  Hauptstraße 12
  70173 Stuttgart

PROBLEMATIC:
  MAX MÜLLER           ← All caps: accepted but not recommended
  Hauptstr. 12         ← Abbreviations: accepted by Deutsche Post
  D-70173 Stuttgart    ← Country code: unnecessary for domestic mail

REJECTED:
  Handwritten addresses
  Font size below 8pt
  White text on dark background (not machine-readable)

• Font size: minimum 8pt, recommended 10–12pt
• Typeface: sans-serif or well-readable serif font (Arial, Helvetica, Times)
• Contrast: dark text on light background

Dialogpost Marking

Every item must be marked as Dialogpost. This is done through:

1. DataMatrix code franking (DV-Freimachung) – the most common method
2. Dialogpost notation in the address area
3. Sender information on every item (mandatory)

Without correct marking, Deutsche Post treats your item as a standard letter and charges the full rate.

Contractual Requirements

Dialogpost is not a product you can simply hand over at a post office counter. You need:

1. Contract with Deutsche Post

Either a framework agreement directly with Deutsche Post or submission through a lettershop that already holds a contract. Most small and medium-sized businesses use the lettershop route.

2. Customer Number

For billing, you need a customer number with Deutsche Post. This is assigned when the contract is set up.

3. Billing Arrangement

Billing is typically invoice-based (not counter-franked). Common models:

• Postpaid: billing after submission
• DV-Freimachung: automated billing via DataMatrix code
• Via lettershop: the service provider includes postage costs in their invoice

4. Submission List

Every submission must include a submission list (Einlieferungsliste). It contains:

• Number of items
• Weight class and format
• Sender and customer number
• Date of submission

Data Quality: The Underestimated Requirement

The formal requirements are well-documented and relatively straightforward to meet. The real hurdle lies in the quality of your address data. Even when format and minimum quantity are correct, faulty addresses cause concrete problems:

Undeliverable Items

Deutsche Post attempts to deliver every item. Invalid addresses produce returns – and you still pay full postage. With a 5% return rate on 10,000 items, that means 500 wasted letters.

Example: 10,000 Dialogpost items at EUR 0.28 each

Scenario A – without data cleaning:
  Returns (5%):        500 × EUR 0.28 = EUR 140 postage lost
  Duplicates (4%):     400 × EUR 0.28 = EUR 112 paid twice
  Print costs:         900 × EUR 0.15 = EUR 135 wasted
  Total wasted:        EUR 387

Scenario B – with data cleaning:
  Returns (1%):        100 × EUR 0.28 = EUR 28
  Duplicates (0.5%):    50 × EUR 0.28 = EUR 14
  Print costs:         150 × EUR 0.15 = EUR 22.50
  Total wasted:        EUR 64.50

  Savings per campaign: EUR 322.50

For larger campaigns with 50,000 or 100,000 items, the savings scale accordingly. More on costs in our Dialogpost cost overview.

Duplicates and Multiple Mailings

When the same person appears under two slightly different spellings in your list, you send two identical letters to the same recipient. This wastes money and leaves an unprofessional impression.

Typical duplicate variations that occur in Dialogpost campaigns:

Hans Meier        | Bahnhofstr. 5     | 80331 München
Hans-Peter Meier  | Bahnhofstraße 5   | 80331 München
H. Meier          | Bahnhofstr. 5     | 80331 Muenchen

Simple text comparisons in Excel or Access cannot recognise these variations as belonging together. This requires fuzzy matching algorithms that account for character similarity, abbreviations and umlaut variants.

Household Duplicates

A special case: two people at the same address each receive their own letter with identical content. This happens frequently with families or shared flats:

Maria Schmidt     | Gartenweg 8       | 50668 Köln
Thomas Schmidt    | Gartenweg 8       | 50668 Köln

When the content is identical anyway, one letter per household is sufficient – addressed to "Familie Schmidt" or "Residents at Gartenweg 8". This household consolidation (Household Merging) saves significant postage on large lists.

Checklist: Dialogpost Requirements at a Glance

Before submitting your next campaign, verify each point:

Quantity and Contract:

• At least 1,000 content-identical items
• Valid contract with Deutsche Post (directly or via lettershop)
• Customer number available
• Submission list prepared

Format and Production:

• Dimensions within specifications (measure, don't guess)
• Weight within limits (weigh, don't estimate)
• Machine-compatible material
• Franking zone and coding zone kept clear

Addressing:

• Address field in correct position
• Font size at least 8pt
• Machine-readable contrast (dark on light)
• Sender information on every item
• DV franking or Dialogpost notation

Data Quality:

• Addresses checked for completeness (postcode, city, street)
• Duplicates removed (with fuzzy matching, not just exact comparison)
• Households consolidated (where appropriate)
• Formatting normalised (street abbreviations, postcode format)

Automated Address Data Preparation

Meeting data quality requirements manually is unrealistic for lists with more than a few thousand entries. Specialised software handles normalisation, duplicate detection and household consolidation in a single pass.

ListenFix is a desktop solution built specifically for this use case. You import your address list as CSV or Excel, run the analysis, and receive a cleaned list that meets Deutsche Post's Dialogpost requirements. Five fuzzy matching algorithms detect spelling variations like "Müller/Mueller" or "Str./Straße". Household detection consolidates people at the same address. And because all processing runs entirely on your local machine, your address data stays GDPR-compliant.

The investment pays for itself quickly: even a single campaign with 10,000 addresses typically saves more in postage and print costs than the software costs. At prices starting from EUR 69 for the Starter version, the threshold is low.

Successful Dialogpost Starts with Your Data

The technical requirements for Dialogpost are manageable: minimum quantity, correct formats, valid contract, proper marking. These points can be systematically checked off with a checklist.

The real success factor runs deeper. Companies that clean their address list before every campaign – removing duplicates, consolidating households, normalising formats – save more than just postage. They reach more recipients, avoid returns and present themselves professionally. Meeting Deutsche Post's requirements is the first step. Clean data is what makes that step worthwhile.