What does a lettershop do?

What a lettershop does, step by step

Which steps a job needs depends on the mailing. An enveloped mailing with a letter, a payment slip and an insert usually goes through these:

1. Taking over the address data

   You supply the address list, and the lettershop brings it into the shape that personalisation and sorting need. Address lists are personal data: if the lettershop processes them on your behalf, the GDPR requires a data processing agreement for it (Art. 28). [4]

2. Personalising and printing

   The letter, payment slip or address carrier gets the address and salutation, depending on the equipment partly or fully addressed by inkjet or laser, or fully individualised in digital print. [3] Parts without personalisation, such as inserts, can also come from a printer. Settle early who prints what.

3. Folding

   The letter is folded to suit the envelope: an A4 sheet folded twice in parallel gives one third of A4 and fits DL and C6/5. [6] The guide to fold types shows the options.

4. Inserting

   The letter, payment slip and inserts go into the envelope, by machine or by hand. [2] What matters here is covered under Inserting below.

5. Sealing

   The posts set how an envelope must be closed: in Austria the flaps are glued right up to the outer edge [7]; in Germany the flap of standard and compact letters is firmly glued along its full length [10]; for Obchodní psaní in Czechia along the full length of the flap. [13] A self-mailer needs no envelope and is glued shut itself; sizes and limits are in the guide to mailing formats.

6. Sorting, bundling and franking

   For advertising and fundraising mail, the lettershop sorts the items as the postal product requires, bundles them and applies postage. Since 1 January 2026, Deutsche Post in Germany only offers franking methods with a digital matrix code. [11]

7. Handing over to the post

   On the agreed date the lettershop hands the items over to the post. Minimum quantities and rules by country are in the table below.

Advertising and fundraising mail: handover by country

As of 23 October 2026; the posts' current terms are what counts. The guide to mailing formats compares the size and weight limits of these products, and the guide to envelope sizes covers the size limits for envelopes.

Inserting: by machine or by hand

Inserting (also called enveloping) means putting the letter and inserts into the envelope and closing it. For larger runs, inserting machines do this. One provider gives as an example lines for sizes C6 to B4 and special formats with up to twelve components, with camera matching and weight checks. [2] Envelopes meant for inserting machines have a standard of their own: DIN 678-2, covering sizes C6 to C4. [5]

Lettershops also work by hand, from folding through inserting and enveloping to franking. [2] Whether a part fits the machine or has to go in by hand is something the lettershop decides from a sample. Ask in particular about:

• special formats and unusually shaped parts
• gifts and other objects in the envelope
• thick or stiff inserts, such as cards made of board
• parts that must lie in a particular position or order

We found no generally valid limits on fill height or thickness for inserting machines in freely available sources. They depend on the line in question, so ask before inserts are produced.

What matters for machine inserting

• An envelope with room to spare. According to one secondary source, DL (110 × 220 mm) is slightly too small for reliable machine inserting; that is why DIN 678 introduced the slightly larger C6/5 (114 × 229 mm) as an alternative. [6] Sizes, contents and postal limits of all formats are in the guide to envelope sizes.
• Fold type. The fold decides how the sheet sits in the envelope and whether the address shows in the window. Agree who folds: the printer before delivery, or the lettershop at the inserting machine.
• Paper and total thickness. All parts together decide the item's thickness and weight. The smallest or machinable format for advertising mail allows a maximum thickness of 5 mm in AT, DE, CZ and SK. [8] [11] [13] [14] For machinable items, the Austrian post accepts smaller inserts up to 200 g/m². [7] The paper weight calculator works out how heavy the mailing will be.
• Order of the parts. Decide which part goes in front and in which order the inserts follow. If several personalised parts belong together, such as a letter and a payment slip with the same address, the machine must match them up; providers mention camera matching for this. [2]
• Window and address. In a window envelope, the address carrier has to sit so that the address shows in the window. In Austria it must be at least 90% of the envelope's length and width. [7] In Czechia only the recipient's address may be visible in the window, and all of it must stay visible even when the contents shift. [12] Window size and position under DIN 680 and the posts' rules are explained in the guide to envelope sizes.

What a request to a lettershop needs

Quotes only become comparable when every provider prices the same job. Include these details in your request:

• Quantities per country, and per version if there are several, for example languages or donor groups.
• Components with size and paper: envelope with or without a window, letter with page count and fold, payment slip, inserts, gifts.
• Who prints what: does a printer deliver parts, or does the lettershop print them itself?
• Data delivery: file format of the address list, fields, character set for umlauts and háčeks, how and when the data is sent.
• Personalisation: which parts, which fields, black and white or colour.
• Postal product per country and who holds the contract with the post, such as the admission contract for Sponsoring.Mail N or the agreement for Obchodní psaní.
• Date of the postal handover, not just of printing. In Czechia the sample must reach the post at least three working days before posting. [13]
• Samples and approval: proof, personalisation sample and a filled sample envelope for weighing.

On Mailingbid you put these details together in one request. Vetted printers and lettershops send comparable quotes, per component and per country. You can also split the award, for example printing to one printer and inserting to a lettershop. For buyers it is free and non-binding.