Variable data printing, and the same idea for email

Variable data printing (VDP) is digital printing in which text, images or codes change from one piece to the next within a single print run, driven by a data file. The USPS describes it as a technique that “allows tailored mailpieces to be printed right next to each other on a single print run”. Each record in the file becomes one finished piece.

This page is for print and direct mail teams. The first half explains VDP the way a print buyer meets it: the data file, the template and the press. The second half shows the same idea in email, where image personalization for email draws each subscriber’s picture when the email is opened rather than when the press runs, and how to run the email half of a mailing from the data file you already prepared for print.

What is variable data printing?

A conventional print run makes many copies of one design. A VDP run makes many versions of one design: the layout stays the same, and named fields in it are filled from a different record for every piece. That is only practical on digital presses, which do not need a new plate for each change. The USPS notes that digital printers can handle quantities “as low as one item”.

The USPS Irresistible Mail page lists what tends to vary on a direct mail piece:

• names, images, text and language;
• coupons and deals based on “browsing history, purchase behavior, or store locations”;
• color and data visualization, “such as a map from address to store”;
• rewards, incentives and loyalty messages;
• custom lookbooks or itineraries;
• “a personalized URL or QR Code” for tracking.

It helps to separate three depths of variation, because they cost different amounts of work. Versioning swaps whole blocks by segment: one cover for the north, another for the south. Personalizing fills fields inside one design: a name, a store, a code. Full customization changes the content of the piece itself per person, such as a lookbook built from what each customer bought. Most direct mail sits in the first two, and so does almost every email.

How is a VDP job put together?

The USPS breaks it into three steps: data collection (“quality data is critical in VDP”), template design “with variable elements in mind”, and digital printing, where the vendor syncs data and design and prints the pieces.

In design software that becomes a data merge. Adobe’s InDesign documentation calls the parts a data source, a target document and a merged document:

A typical data file for a store-opening postcard looks like this:

first_name,store,code,@StorePhoto,#QRCode
Maya,"Leeds, Briggate",LDS-2611-MAYA,/Photos/leeds.jpg,URL:https://example.com/s/LDS-2611-MAYA
Tom,"Bristol, Park Street",BRS-2611-TOM,/Photos/bristol.jpg,URL:https://example.com/s/BRS-2611-TOM

Two details catch people out. A store name with a comma in it has to be in quotation marks, as Adobe’s page notes, or the comma splits it into two fields. And every image path has to exist on the machine doing the merge, which is why print shops ask for the photos and the data file together.

The same idea in email, at open time

An email campaign with a picture per person has the same three parts. The data file becomes a recipient list. The target document becomes a template with variables. The press run becomes a set of image addresses, one per row, and each picture is drawn when that subscriber’s mail client asks for it.

Here is the email half of the postcard above, drawn by the EmailTimer.app engine from one template and the same names, stores and codes:

To build it in EmailTimer.app on the Growth or Agency plan (see pricing):

1. Save a copy of the print data file with only the columns the email needs, and add an email column. Drop the @ and # columns: an email template does not read file paths, and its QR code layer takes the value directly.
2. In the editor, design the template with variables named after your columns: a text layer reading {{first_name}}, a gift is waiting at, another reading {{store}}, a text layer and a QR code layer both drawing {{code}}.
3. Upload the CSV as a recipient list. A row that cannot be read is reported with its line number and the reason, and the rest imports.
4. Export one signed image address per row and import it into your email platform as a contact field.
5. Proof it: preview the template with two or three real rows, then send yourself a test.

Store photos work too, with one change from InDesign. Instead of a path per row, you upload the photos to the template once and an image layer picks one by a value in the row, such as the store’s short name. Image mail merge compares the file-path way and the email way in more detail.

Where print and email differ

The second row is the one a print team does not have. On paper, “this weekend only” stays on the fridge after the weekend ends. In email, a rule on the time of opening can swap the line, hide the code or show an ended state once the offer is over, so a late reader is not sent to a store with an expired code.

The reverse is also true. Data visualization such as a map from each address to the nearest store is on the USPS list for print; EmailTimer.app does not draw maps, and it does not fetch outside data while drawing. A store’s name, photo, address line and opening hours from your data file are what the email image can show.

For teams that send named awards or completion documents to a list, the same file-to-image flow covers certificates by email. For a broader view of how far per-person content can go in email, hyper-personalization sets out what needs data you may not have.

Running a mailing and its email together

When the postcard and the email are one campaign, keep these the same across both:

• the code each person gets, so either one works at the till;
• the store each person is sent to;
• the offer’s end date and time, written the same way;
• the suppressions: email opt-outs come off the email list and mail opt-outs come off the mail list, each checked on its own.

Then plan the timing. A printed piece arrives on whatever day the post delivers it, across a spread of days. An email lands when you send it. Sending the email to arrive around the expected delivery date, rather than days ahead, makes the two feel like one message.

Questions and answers

What is variable data printing used for?

Direct mail where each piece carries the recipient’s own details: name, nearest store, offer code, loyalty reward, a personalized URL or QR code. The USPS lists all of these as common uses.

What file format does variable data printing use?

Usually a CSV or other delimited text file, one record per row with field names in the first row. InDesign marks image columns with @ and QR code columns with #.

Is there variable data for email?

Yes. A recipient list plays the part of the data file, a template with variables plays the part of the print layout, and each row gets its own image address that draws that person’s picture when the email is opened.

Can I use my print data file for the email?

Mostly. Keep the columns the email needs, add an email column, and remove the image path and QR code columns, since the email template uploads photos once and draws QR codes from a value.

What can email do that a printed piece cannot?

Change after it is sent. A rule on the time of opening can swap the offer line or hide an expired code, and a countdown shows the time left at each open.