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November 3, 2021

Creating Beautiful and Functional Print Mail From Digital Assets

Sid Maestre

Creating Beautiful and Functional Print Mail From Digital Assets

Creating and automating beautiful and functional print mail from digital assets is an important, innovative step toward saving time while getting the most out of all marketing channels. Automating direct mail has been a challenge for many businesses over the years. This article is an excellent start to learning how Lob efficiently solves this challenge.

Lob is a data-driven company that provides user-friendly direct mail and address verification APIs. The APIs enable businesses to automate direct mail by helping send personalized mail automatically. It also handles converting digital materials to print mail assets using the Lob API, saving time and resources.

Flexibility is critical, so the Lob API can accept HTML templates and PDF, PNG, and JPG files. Using Lob, you can:

  • Convert PDF files into HTML and incorporate PNG and JPG files directly into HTML templates.
  • Use easily editable HTML templates at any time with only basic HTML knowledge. We can automatically customize HTML templates for personalized mailings. Also, we can save and reuse HTML templates.
  • Use inline CSS or internal CSS stylesheets. Without CSS, the template appears as a plain HTML page. So, this option enables you to add some style.
  • Use a gallery of HTML templates as a jumping-off point when building Lob templates.

Let’s review a hands-on demonstration of how you can leverage Lob’s APIs to prepare photos for a postcard efficiently.

Creating print mail from digital assets

The most effective way to translate digital assets to print is using HTML templates. With inbuilt templates, developers and content creators only have to prepare content as an HTML template, then mail it using the Lob API. The API does all the necessary heavy lifting and makes the process seamless for users. 

Let’s use a PNG file to explore Lob and format it for inclusion in a Lob postcard template. You first need to sign up for a free Lob account. This action directs you to Lob’s dashboard to get started. The helpful dashboard provides a holistic view of essential information. 

Next, we'll choose a royalty-free PNG file from Unsplash:

The PNG file is unformatted, so you go to your Lob dashboard to turn the image into a postcard. The Postcards section on the dashboard enables you to print and mail postcards easily. You can create, edit, and view Lob templates on the dashboard

This process also gives you more details about the size of the PNG file and its compatibility with Lob postcard standards. Postcards allow you to enter a description and address, making the design more exciting and simplifying the challenges of designing digital assets.

As you can see in the above video snippet, Lob gives you the expected size for the PNG file. In cases when you aren’t sure of your file size, this tool is invaluable. Additionally, Lob’s design guidelines section gives you best practices to follow when creating and designing content. 

As you use Lob, understanding the design guidelines helps apply the proper formatting for your files. Let’s look at some of the top design guidelines for Lob templates before you edit the PNG file:

  • The bleed area is the extra space included to ensure that the artwork prints to the edge. For example, the file size for postcards is 4.25” x 6.25”, more than the standard 4’’x 6”. The extra 0.25’’ is the bleed area. This area is beneficial because artwork, by default, has larger dimensions when printed.
  • The safe zone is where you keep all text to ensure no essential details are lost. You can think of this area as safeguarding your content.

Lob also has HTML template standards. The standards in these templates are straightforward when you use Lob’s API. Let’s explore some of these standards:

  • To obtain the best performance for your application, you need to use a performant file hosting provider, such as Amazon S3, for linked assets. 
  • Use inline styles or internal style sheets only. Don’t link to external stylesheets mainly because the templates may not render correctly until the external stylesheet loads.
  • Ensure to link 300 dots per inch (DPI) images at the physical mailing’s final desired size to prevent blurry prints. For example, your royalty-free PNG file hasn’t met the prescribed size. A little later, we’ll edit the file to get the desired size according to Lob standards.
  • The sum of all linked assets should not exceed 5 MB.
  • Use WebKit prefixes for CSS properties. WebKit is a web browser rendering engine used by Safari and Chrome, among others. Because different browsers have varying user-agent styles, it’s good to check what prefixes newer CSS properties need.
  • Lastly, use Canva, Adobe Illustrator, or Adobe Photoshop to design content for the Lob API. These tools provide the most flexibility and export options. Of course, there are many other photo editing and resizing tools at your disposal, too.

Adding images

In this section, we’ll dive into using a PNG file that works with Lob’s API via Canva. This section is beneficial if you haven’t used Canva before. It’s also a good refresher for experienced users.

Submitted images must have the same height to width ratio as the chosen product — in this case, postcards. The API doesn’t crop or stretch the image. To ensure that you produce a PNG file that meets the proper dimensions with a 300 DPI setting, in this example you'll use Canva to resize your PNG file.

You'll crop the file to match the correct size that Lob expects for the PNG file. Recall that you saw those specifications in the dashboard’s Postcard section.


Now you can save your resized file, export it as a PNG file, and go back to creating your postcard in the Lob dashboard. Let’s get to it.

Using the Lob dashboard

From the video snippet above, you can see that editing the PNG file to the expected size results in a high-quality postcard that’s ready to send out. Ensure you are in Test mode, choose that file, click Create, and review the new postcard design.

Here is your final postcard with the photo on the front and the photo and postage information on the back. You can further customize your postcards with a different image (or none at all) on the back.


In this hands-on demonstration, we’ve explored how you can leverage Lob’s APIs to seamlessly prepare print mail from digital assets, such as the PNG file we used. With solid templates and documentation, Lob is an excellent platform for all print and mail needs. All you need to do is prepare the content you’d like to print and pass the requests to Lob. 

Standard HTML and CSS tools also enable team members with diverse skill sets to collaborate when preparing print mail digital assets. Once you feel comfortable, use Postman, a vital tool for sending API requests to your applications. When you’re ready, learn about pairing Lob’s APIs with Postman.

There are so many possibilities for how you can translate your digital assets with Lob. When you’re ready to send innovative and personalized mail, try Lob to wow your customers and create a more efficient direct mail process.

This blog provides general information and discussion about direct mail marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.

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