What direct mail production involves after the press

Printing a mailing is only half the job. A campaign of 20,000 letters, postcards or catalogues still has to be personalised, folded, matched to envelopes, sorted and handed to a postal operator in a format they accept. Each of those steps is a production process with its own machines, tolerances and failure points. When a mailing goes wrong, it is rarely the printing. It is usually a data file with blank address lines, a letter that does not quite fit the envelope window, or a sort that the postal service refuses.

This guide walks through direct mail production in volume: the formats that run efficiently, how addressing and personalisation are done, how folding and inserting machines work, what makes mail machinable, and how to plan the schedule so a mailing lands when the campaign needs it.

Choosing a mail format that runs well

The format decides which machines the job goes through and often how much the postage costs. The main choices are:

Postal operators publish size, weight and thickness ranges for each price band, and these differ between countries. Check them before design starts. A postcard a few millimetres too large, or a letter one gram over a weight step, can push the whole campaign into a more expensive postage tier.

Addressing and personalisation

Most volume mail is personalised: a name and address at least, often a personal greeting, a customer number or a different offer per segment. There are two main ways to get the data onto the piece.

• Digital printing with variable data. The whole letter, including the address and personalised text, is printed in one pass on a digital press. Good for short and medium runs and for heavy personalisation.
• Offset shells plus inkjet addressing. The static design is printed by offset in a long run, then a high-speed inkjet head adds the address and any variable text in line. Cost effective for large volumes with light personalisation.

On coated or laminated stocks, inkjet addressing needs a compatible surface, otherwise the ink smears. Leave the address panel uncoated, or confirm that the inkjet system is set up for the coating used. Our article on varnish, aqueous and UV coating explains why the coating choice matters here.

Preparing the data file

The data file is the part of a mailing most likely to cause problems. Before it reaches production:

• Remove duplicates and test records.
• Clean names and addresses against the national address database where a service is available.
• Check field lengths: very long company names or street names need a rule for wrapping or shortening.
• Agree a sort order with the printer, usually by postcode, so pieces leave the machine in postal sequence.
• Supply a short sample of records with unusual characters, so accents and special letters are checked on a proof.

Proof personalised mail on real records, not only on the dummy "Jane Smith" entry in the template. The longest name and the shortest address are the best test cases.

Folding and inserting

For enveloped mail, letters are folded and inserted by machine. A typical inserter feeds the letter, folds it, collects any extra inserts from feeder stations, pushes the set into the envelope, seals it and outputs it in order. Many lines read a code on the letter so that each envelope gets the correct number of pages and the right inserts for that recipient.

• Folds must be accurate. If the address does not sit squarely inside the envelope window, the post cannot read it. A letter fold tolerance of a millimetre or two matters. The general principles are in our guide to folding methods.
• Inserts need to fit. Leave enough clearance between the folded set and the envelope, often a few millimetres on width and height, so the machine does not jam.
• Paper behaves differently. Heavy or freshly printed stock can crack on the fold or mark other pages. Scoring before folding and allowing ink to dry fully both help.
• Envelopes vary. Window position, flap style and gum type must match the inserting machine. Order envelopes after the insert sizes are fixed, not before.

Inserting sits within a wider family of finishing tasks; see collating, inserting, shrink-wrapping and kitting for how they connect.

Making mail machinable

Postal services sort huge volumes automatically. Mail that their machines can handle usually gets the best price. To be machinable, pieces generally need:

• Dimensions and thickness within the operator's ranges.
• Enough stiffness, so a postcard does not bend and jam.
• A clear address area with good contrast and no patterned background.
• Space reserved for any postage indicia, barcodes or franking marks the operator requires.
• Self-mailers sealed according to the operator's rules on tabs or glue lines.

Many postal services publish design guides and offer a check on samples before a large campaign. Use them. A rejected mailing at the post office costs far more than a sample sent two weeks earlier.

Quality checks during a mailing run

Personalised mail needs checks that a static print run does not. On a well run mailing line, operators pull samples at regular intervals and compare them with the data file: is the name on the letter the same as the name in the window, does the page count match, are the right inserts in the envelope? Camera systems on many inserters read a code on each letter and stop the line if a piece is missing or duplicated. Even so, a few habits help:

• Add seed records, such as your own office address and a few colleagues, so you receive real pieces from the live run.
• Keep a log of spoiled pieces and reprint them from the data, so every recipient still gets a mailing.
• Check the first and last trays of each sort, where machine settings are most likely to drift after a restart.

Matching the printed run against the delivered quantities is covered in more detail in our guide to quality control on a print run.

Scheduling a large mailing

Direct mail campaigns usually have a target "in-home" date, when the piece should arrive. Work back from it:

1. Postal delivery time for the service level chosen.
2. Hand-over to the postal operator, often on a booked slot.
3. Inserting, sorting and packing into trays or bags.
4. Addressing and personalisation.
5. Printing, drying and any finishing.
6. Data approval and proof sign-off.

Build in time for overs and spoilage. Inserting lines spoil a small number of pieces during setup and running, and personalised pieces cannot simply be replaced from stock. Our article on make-ready, spoilage and overs explains how printers plan for this.

Producing your direct mail campaign with us

We handle direct mail from print to post: digital and offset printing, variable data, inkjet addressing, folding, inserting and sorting in postal sequence. We check your data file before production, proof on real records, and confirm formats and weights against the postal rules for your mailing so there are no surprises at hand-over. Each campaign gets a production schedule worked back from your in-home date.

Find out more on our general printing services page, or contact us with your quantity, format and target date, and we will suggest a production route and a timeline.