Direct Mail

Direct Mail API

By 28 February 2024April 16th, 2024No Comments
address geolocation

Get Started with PostGrid’s API in Seconds

Easily send direct mails, manage templates and verify addresses globally using API



curl \
-u API_KEY: \
-d to[firstName]="Kevin" \
-d to[lastName]="Villena" \
-d to[addressLine1]="145 Mulberry St, Apt PH D, New York, NY 10013" \
-d to[countryCode]="US" \
-d from[companyName]="PostGrid" \
-d from[addressLine1]="90 Canal St, Suite 400, Boston, MA" \
-d from[countryCode]="US" \
-d color=true \
-d express=true \
-d template="template_4hXPyVphgFPynPyHFTJaKo" \
-d mergeVariables[verification_code]=4242
Read our API Docs



curl \
-u API_KEY: \
-d to[firstName]="Kevin" \
-d to[lastName]="Villena" \
-d to[addressLine1]="145 Mulberry St, Apt PH D, New York, NY 10013" \
-d to[countryCode]="US" \
-d size="6x4" \
-d frontTemplate="template_6a3k5LqumLD7cpdD9VkQUd" \
-d backTemplate="template_oa8Au5h4DqFr1mRDLaKhJz" \
-d mailingClass="standard_class" \
-d mergeVariables[qr_code_url]=""



curl \
-u API_KEY: \
-d to[firstName]="Kevin" \
-d to[lastName]="Villena" \
-d to[addressLine1]="145 Mulberry St, Apt PH D, New York, NY 10013" \
-d to[countryCode]="US" \
-d from[companyName]="PostGrid" \
-d from[addressLine1]="90 Canal St, Suite 400, Boston, MA" \
-d from[countryCode]="US" \
-d bankAccount="bank_k9zDtHjZmBe9ruVC4F8PZN" \
-d amount=4242 \
-d message="Here is the payment for the attached invoice." \
-d letterPDF=""


# List all letters destined for New York that have left their final USPS facility. curl "NY out_for_delivery" \ -u API_KEY: # Retrieve a check and its corresponding bank account curl[]="bankAccount" \ -u API_KEY:


# Automatically parse and correct a freeform US or Canadian address curl \ -u API_KEY: \ -d address="14-20 bay st, floor 11, toronto, on, canada" # Use our international API to verify addresses around the world curl \ -u API_KEY: \ -d address[line1]="33 Nine Elms Lane" \ -d address[city]="London" \ -d address[postalOrZip]="SW11 7US" \ -d address[country]="United Kingdom"


# List US & Canada previews for partial address input curl \ -u API_KEY: # List addresses from around the world, sorted by distance to user IP curl \ -u API_KEY:

Seamless Solution for Your Direct Mail Marketing

Strengthen your B2B relationships with an easy-to-use all-in-one solution –  PostGrid. With us, you can send personalized direct mail for more customer engagement, automate the entire direct mailing process using direct mail automation software to save time and resources, track the ongoing campaigns and get their analytical reports to improve your future campaigns, and integrate your enterprise system or website to fetch tons of data within seconds.

Let’s discover how it helps you improve your relationships with clients or prospects.

How It Helps You Improve Your Relationships With Your Customers

Instead of opting only for online solutions, when you send to your potential or existing customers and clients, personalized tangible direct mail creates a higher impact and makes the receiver feel valued. Plus, the open rate of direct mail is way higher than email, and it helps you grab the opportunity instantly. In addition, direct mails have a response rate of 5.1% better than any other digital marketing strategy as – even today – people love to receive postal mail.

So, grab this opportunity, and start sending direct mail to your customers without investing much time with the help of PostGrid and improve your return. We’ll discuss the further benefits of direct mail API and postal API in detail.

direct mail marketing for law firms
implement zip code direct mail api

What Is a Direct Mail API

A direct mail API lets you automate your direct mail – just like email – with the help of direct mail software like PostGrid. All you have to do is integrate it with your CRM, eCommerce, or marketing platform. Once done, the system sends direct mail based on your prospects’ or customers’ actions.

With the help of direct mail software like PostGrid, you wouldn’t need to worry about running out of ink, missing out on sending an emergency direct mail, folding the letters, putting them in the envelopes, running back and forth to the post offices, and other tedious tasks.

There are many more benefits of API, let’s understand them in detail.

Why Use Direct Mail API to Automate Your Mailing Campaigns?

A direct mail API, like PostGrid, enables you to be flexible and agile when planning and executing your campaigns. You can plug our high-tech features into your workflows or business processes to get the best of both ecosystems.

It helps you benefit from direct mailing without starting from scratch or building automated campaign wizards.

APIs enable companies to weave their favorite tools and applications to suit their requirements and execute well-planned marketing plans. And PostGrid’s API does just that!

It eliminates manual and time-consuming processes to replace traditional mail with modern, automated mailings.

PostGrid is your all-in-one solution to send custom marketing, compliance, and other items online—without doing anything in-house.

Unified Offline API

More reasons you must use a direct mail API:

  • Personalization: Interpolating your prospects’ and customers’ data into your mailers can help you add a personal touch to your campaigns. You can customize your messages to outperform other companies sending generic mail. PostGrid’s direct mail API offers variable data printing capabilities to let you personalize mail at scale. Thus, you can create and ship unique items to every recipient based on their needs and preferences to improve conversion rates.
  • Professionally-built postcard and letter templates: Choose from our in-built mail designs to save on costs and create your artwork yourself. You can add your company’s logo and make other changes, branding your mailers to add your feel and touch. Also, making last-minute changes is no longer hectic or problematic. Create and save artwork whenever needed with PostGrid’s direct mail API.
  • On-demand print and mail fulfillment: Many refer to direct marketing as ‘snail mail” because it takes many days for your items to reach the targeted audience. However, our direct mail API can speed up your mailings by helping you plan campaigns whenever needed. You can also schedule your programs for a date of your choice. PostGrid ensures you can mail whenever you want and to whoever you want. Our API also cross-checks your delivery addresses with the USPS’s authoritative database to guarantee high and accurate deliverability.
  • Popular API integrations: Businesses can integrate PostGrid into HubSpot, Salesforce, Marketo, Zapier, ActiveCampaign, QuickBooks, and other platforms and tools. Our zero-code and native integrations make connecting applications and expanding functionalities a breeze.
  • Document rendering: PostGrid’s direct mail API can convert your HTML files into PDF for effective and hassle-free printing. You don’t need to worry about your mail formats. We help you maintain regulatory compliance, render PDFs, and save records for future use.
  • 2-business-day SLA: Get your mailers ready and out the door in only two working days. PostGrid processes your orders of all sizes on priority, helping you reach your audience and make an impression faster!
implement zip code direct mail api

Benefits of Direct Mail API

Fully Automated

With an automated direct mail system, like PostGrid, you can trigger each of your direct mail, whether it’s a welcome mail, thank you mail, confirmation mail, invoice, monthly report, or anything. Plus, you can also personalize them in terms of design, and message, and send targeted mail to the right user. Once set, you can forget about it and let our system do the job for you, each time a person enters your campaign


The safety of our client’s data and sensitive information is our number one priority at PostGrid. Hence, we make sure that every transaction or other data shared remains confidential. Besides that, PostGrids has a highly compliant and secure print and mail processing partnership ensuring you are able to boldly send any direct mail containing any kind of data whether sensitive or simple marketing message with trust.

Strengthen Customer Relationships

Without you getting involved in any tedious tasks, your customers will continue to receive direct mail with the relevant offers and discounts that you have to offer, the birthday or anniversary mail, other thank you, sorry, query, or follow-up mail. Hence, these letters will help you maintain good relationships with your customers and save you time and resources.

Enhance Customer Engagement

It keeps them engaged with your company and products, and eventually, your brand remains at the top of their minds. Send highly personalized and targeted mail with relevant offers pertaining to the right users. The entire process will run automatically and you won’t need to invest your time in any of the steps.

Multiple Industries

With PostGrid Direct Mail API, all industries like real estatefinancebanksnonprofitslaw firmsB2B, healthcare, educationfintech, and many other sectors can benefit.

Test and Launch

PostGrid allows you to test your campaigns before launching them in front of a large audience, get the analytical report, and find out whether it will work out or not. This practice will save you tons of time, money, and resources that you will put into this campaign.

Show Professionalism

Manual tasks, along with being tedious in nature, open the gate to loads of errors. It may stand in the way of your company’s good reputation. Using a direct mail automated tool, like PostGrid, you can get rid of all the tiny errors, and unnecessary delays, and trigger on-time delivery, furthermore, showing off your company’s professionalism. And eventually, with regular direct mail, increase your brand awareness, and engagement, and get a higher customer retention rate.

Analytical Reports

By integrating your CRM with PostGrid, you can track all of your launched campaigns by getting regular reports or by checking them from your dashboard. Beginning from tracking your direct mail processing, printing, shipping, and delivery to getting the final analytical reports on the performance of your campaigns, you can get every tiny detail from your dashboard. This way, you can significantly improve your customers’ engagement, retention, and repeat business, and garner high returns.

Full Control

You can manage everything yourself without relying on your different teams and departments, designers, writers, printing, and postal services. Easy implementation with detailed API docs and dev support, seamlessly integrates with your current CRM without changing your existing workflow through PostGrid’s Direct Mail API, and has added capabilities to send personalized letters, postcards, and cheques.


If you’re looking for long-term benefits and really want to know how an automated system can be budget-friendly, then calculate the cost price of your launched campaigns. The time, money, effort, and physical and human resources you invested without being able to track any of them will turn out to be more expensive than investing in an all-in-one solution.

How Does Direct Mail API Work

The direct mail API works in the following ways

  • Integrate your CRM, eCommerce, or enterprise system with the direct mail service software.
  • Fetch all the data – names, addresses, and other contact information – from your system within seconds.
  • Create customized direct mails such as letters, postcards, and checks using our letter APIpostcard API, and checks API.
  • Set the trigger-based direct mail campaigns in your CRM and automate the entire process with direct mail API.

This process can help you send regular direct mail to your prospects and customers without any interruption and eventually increase your brand awareness, strengthen your relationships with your clients, and revamp your returns.

Features of PostGrid's Direct Mail API

Integrate and launch

Launching direct mail can be daunting when you have to manually do all the tasks. Plus, tedious tasks can also open the door to countless errors that can, sometimes, create massive problems for your brand. Hence, data automation is almost always the best solution. With PostGrid, you can incorporate your CRM, eCommerce, or enterprise system and fetch your customers’ details within seconds. It not only saves you time but also helps you maintain your professionalism, which later on turns out to be quite useful for the company’s reputation.

Scale any time

Whether you need to send one or one thousand direct mail, on PostGrid, we allow you to launch a direct marketing campaign of any number of mailers. Plus, you can also scale your campaigns at any time without worrying about any of the processes involved. From printing to delivering your exact mailpieces to the right addresses is totally our responsibility.

Send Emergency Letters

Oftentimes, businesses face the need to send emergency direct mail, viz., invoices, query letters, or any other type of direct mail. With an automation tool, like PostGrid, in place, you can send these emergency mailpieces, despite the number, at any time.

Customize for Better Engagement

Launching personalized marketing campaigns is no longer a choice; it’s a necessity. If you want to outdo your counterparts, sending customized direct mail can go a long way. This approach can help your customers feel valued and trust your brand even more. So, choosing a direct mail API software that makes personalization simple and easy for you is only wise. With PostGrid, you can customize each of your direct mail – even if it’s a general invoice – by just setting up the system accordingly from your dashboard. It eventually helps you receive more customer engagement and better responses in return.

Easy to use

With PostGrid, you can launch your personalized direct mail marketing campaigns by controlling everything from your dashboard. To get started, create and save the design of your mailpiece, viz., letters, brochures, catalogs, postcards, or any other mailer. Fetch your customers’ list from your system by integration, or get a highly targeted list. Once it’s done, have your uploaded or fetched customers’ details verified with our address verification software. And finally, launch your campaign. (The detailed process is discussed in the later section.

Track and Analyze

When you launch your direct mail promotions using PostGrid, we send you regular notifications on the location of your mailpieces. And once they’ve been delivered to the targeted recipients.

Modern, RESTful API to Suit Your Needs

send certified mail letters

You can use PostGrid’s RESTful API to send personalized direct mailers from your existing systems. This fast and digitized approach to offline mailing lets you ship postcards, letters, checks, invoices, and other items without your staff having to figure out —

  • How to build templates?
  • How to trigger mailings?
  • How to measure direct mail?

PostGrid offers a ready-to-use solution for your business via its modern API integrations that are developer-friendly.

  • Integrating our API into your CRM or website enhances data accessibility and visibility. Also, it allows for quick and seamless connections with networks or systems that can drive more business to your brand.
  • Your developers’ team can use any library, framework, or programming language supporting JSON and HTTP actions to get started!

Triggered and List-Based Campaigns

  • Companies pre-plan list-based campaigns—shipping your marketing and transactional items to an existing mailing list.
  • Triggered direct mail works differently. You can set up action-based triggers to automatically send relevant mailers to your customers and prospects.
  • PostGrid’s direct mail API allows you to send triggered and list-based mailings by completing a few quick steps after the integration. You can automate everything, from preparing and printing your mail to shipping and real-time tracking. It saves money, time, and effort and produces better results!
web to print api

What API Functionalities Can You Expect On Integrating PostGrid?

direct mail design tips
  • Create or upload contacts: PostGrid allows you to add your mailing lists to your account for current and future use. You can import a file from your device or enter recipient information on-demand to send individual mailers. Our API also lets you compile customer data based on geo–demographics like location, age, gender, profession, and more.
  • Select mail sizes and delivery options: Choose which mail format and size you want to send in your upcoming campaign. You can also decide the mailing speed, as we have many options, including First-Class, Standard, Registered, Marketing, and Express Mail.
  • Send your mailpieces: Create print and mail tasks within your CRM or website via our API integrations. You can send mailers whenever needed and get real-time updates and analytics to monitor progress and performance.

When to Use a Direct Mail API for Mailing Campaigns and CRM Integrations

Direct mail marketing campaigns help businesses in all industries boost their sales and brand image—healthcare, insurance, or real estate.

Here are some of the best use cases for using a direct mail API to enhance your marketing mix:

restful api
  • Improve customer loyalty: Use PostGrid’s direct mail API to tailor your offline messages and make recipients feel special. You can foster brand loyalty and boost retention rates by staying in touch with your existing customers while acquiring new leads.
  • Greet customers on special occasions: Send holiday, birthday, and anniversary greetings to grab your intended audience’s attention. It increases your company’s publicity, reminds people of your products and services, and prompts them to buy from you.
  • Reduce shopping cart abandonment: It is time to ditch automated emails that most people skip. PostGrid’s direct mail API lets you send custom mailers to prospects, reminding them to complete their checkouts. This practice ensures you don’t miss out on any sales opportunities and have a steady income flow.
  • Launch omnichannel marketing programs: A direct mail API is the simplest way to connect your direct mail, email, social media, and CRM. It lets you go omnichannel to expand your outreach and spread brand awareness.

FAQs About PostGrid

How Does PostGrid Works For Printing and Mailing Letters?

PostGrid is a Print and Mail API for managing the printing and mailing of all types of direct mail. Its usage is relatively easy. All you have to do is:

  • Select a template and fill in the details of your message, upload your own template, or create a design from scratch.
  • Upload the CSV file of your contact list, or integrate PostGrid with your system and fetch all the data within seconds.
  • Get all the addresses verified with our – free of cost – address verification software for reducing the bounce rate, misspending, and lost opportunities.
  • Track all of your letters campaign from printing, processing, and shipping to final delivery.
  • Get analytical details of all of your campaigns to improve your future campaigns and get better returns.
  • Automate every process and launch future campaigns with a single click.
  • Control everything from a single dashboard.
  • Get better deals at per-piece printing.

Are PostGrid Direct Mail API Processes HIPAA compliant?

Our services and facilities are HIPAA compliant for customers who need them. To ensure your documents comply with HIPAA, please contact sales to get a BAA signed.

What Product Specifications for Direct Mail Letters are Available at Postgrid?

Our commercial printer network uses a few pre-approved papers. Every paper source specification must fall within a small range to ensure uniform quality and consistency. The following specifications and ranges are provided:

US & International size guidelines are:

  • 6×4
  • 9×6
  • 11×6

Other Specifications:

  • Basis Weight: 60# text
  • GSM: 89 – 90
  • 10% PCW Product
  • FSC Certified

You can find product specifications related to the specifications of our API to send direct mails here.

How Much Does PostGrid's Direct Mail API Cost?

Please get in touch with us to learn about your needs and offer the best solutions and pricing.

How Much Can I Save if I Decide to Use Postgrid?

With PostGrid, you save money by getting the best deals on per-piece printing due to our vast sending volume. Using our address verification software, you can save the amount you’ll spend on letters addressed to the wrong audience or sent multiple times to the same person. Besides that, you can save time, effort, and resources that would otherwise be spent on doing tedious tasks manually.

What is PostGrid’s Day-to-Day Cut Off Times for Letters?

We accept submissions until 10 am PST each day; anything received after that time will be processed on the next production run. If your send date overlaps, a daily cut-off time with the cancellation window or scheduling feature will be slotted into the next production day. This includes all public holidays and normal business days.

Can I Send Letters Containing Sensitive Information?

All our partners are PIPEDA/HIPAA compliant, and hence you can send any letter containing any sensitive information through our API to send direct mail. You can easily send billing statements, checks, invoices, financial statements, compliance notices, or any other type of mail to us.

How Long Would I Need to Wait for the Delivery of My Letters?

PostGrid offers the industry-best SLA ranging from the same day to 2 days for the handover of your collaterals to local postal service providers for delivery.

How Does the Payment System Work at Postgrid Direct Mail API?

You can use any method of payment that you’re comfortable with, for example: receiving invoices, credit lines, PayPal, credit cards, bank transfers, etc.

Does PostGrid Offer eReceipts of Return?

Definitely, you will get all the information related to your print and mail by integrating our direct mail API! The USPS offers a Certified Mail add-on that allows the sender to receive an Electronic Return Receipt. This receipt allows you to download a digital copy of the recipient’s signature. The “extra_service” parameter of creating a letter gives you the option of creating an Electronic Return Receipt rather than a certified return receipt.

On the USPS website, the certified tracking number will enable you to access the return receipt. The following steps will assist you in receiving the signature PDF via email:

  • You can visit
  • Under the section- Track a Package by entering the Certified tracking number
  • Fill out the required fields under “Return Receipt Email”

What Additional Mail Services Do You Offer?

Our Print & Mail product offers the following additional services:


  • Certified Mail – Track domestic mail using the US Postal Service
  • Registered Mail – Track international mail using the US Postal Service for Registered Mail
  • Electronic Return Receipt – This indicates that the package has been delivered


Also, our other services include invoices, checks, and envelope printing. All you have to do is integrate our direct mail API with your CRMS and other system solutions. You can find a detailed list of our offerings and their associated prices by visiting our pricing page.

What is The Most Accurate Way to Know If My Letter Will Require Additional Postage?

If you are wondering how I send a letter with direct mail API- There is a flat fee of $2.00 for each additional page over 6 pages single-sided and $12.00 for letters over 12 pages double-sided. For more information, please visit our pricing page.

Ready to Get Started?

Start transforming and automating your offline communications with PostGrid


Explore Direct Mail

Send direct mail as easy as email through our dashboard or API