Trusted by 1000+ Customers
Letter Mail API Sample Requests for Easy and Simple Setup
Execute actions with intuitive SDKs for multiple programming languages and integrations.
- Create Letter
- Create a Letter with a Template
- Create a Letter with a Template and an Attached PDF
- Create a Letter With PDF
- Create a Letter With a PDF Link
- List Letters
- Cancel Letter
- Cancel Letter With Note
- Progress Test Letter
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LoadingBenefits of PostGrid Letter API
The simplest way to print and send physical letters without wastage or manual labor.
01
Dynamic Personalization
Use Variable Data Printing (VDP) and merge variables to personalize individual mailers with recipient-specific information in seconds.
02
Save Cost & Time
No investment required for expensive printers, toners, storage, or a dedicated staff to manage letters, saving valuable resources.
03
Scale on Demand
Send two or thousands of letters, depending on unique business requirements, without bottlenecks or expanding existing resources.
04
Always Up-to-Date
Rely on a secure cloud infrastructure to forget about updating printing technology or software versions, reducing technical overhead.
05
Reduce Wastage
Access built-in CASS-certified address verification capabilities to validate mailing lists before generating and sending letters.
06
Real-Time Tracking
Monitor accurate delivery statuses of individual letters using USPS Intelligent Mail barcode (IMb) tracking via webhooks.
07
Automated Workflows
Sync data from existing systems to autopopulate content and trigger letters based on real-time events without manual errors.
08
Reporting & Collaboration
Access analytics and enable distributed or remote teams to work collaboratively on letters with a centralized dashboard.
First-Class Developer Experience
Built for developers who prioritize speed, flexibility, and ease-of-use.
Use zero-code integrations to make the integration process faster and easier.
Access SDKs available in multiple programming languages for faster deployment.
Experiment in a sandbox environment before switching to a live environment.
Get real-time notifications for every state change in any workflow or CRM in minutes.
No commitments with a pay-per-piece model to scale according to changing requirements.
Use custom logic to automatically rotate, resize, or extract information from PDFs directly.
Create and manage sub-organizations to separate letter data and define billing metrics.
Integrate a visual template editor within native apps to customize design and layouts.
Embed custom QR codes and PURLs to gather valuable insights once recipients scan the letter.
Send via First-Class, Priority, Priority Express, or Standard class with Registered and Certified Mail.
Sideload entire address books by uploading CSV files to fetch contact information from the dashboard.
Update outdated mailing addresses against the National Change of Address database for better deliverability.
Get Started With the API
Turn each CRM event into end-to-end printing and mailing fulfillment for letters in three steps.
- Connect the API
Integrate the REST API into existing tech stacks by accessing live or Test keys from the dashboard. - Configure Templates
Use the HTML editor or upload pre-formatted PDF assets with merge variables to scale personalization. - Trigger Letters
Set up custom workflows with automated JSON payloads to trigger printing and fulfillment of letters.
Built for the Workflows That Matter
Generate mailers for diverse use cases and regulated industries.
Invoices & Statements
Trigger physical invoices and statements upon transaction completions for faster payment cycles.
- Monthly account statements
- Transaction invoices
- Subscription renewal bills
- Annual tax summaries
Compliance & Legal Notices
Handle important regulatory updates and legal notices with a secure infrastructure using Certified Mail.
- Annual privacy notices
- Policy change disclosures
- Class action settlements
- Contract amendment notices
Collection & Overdue Notices
Send automated payment reminders to fix debt recovery workflows and ensure smooth cash flow.
- Debt collection letters
- Payment default letters
- Debt settlement offers
- Account suspension letters
Welcome Kits & Onboarding
Make onboarding experiences swift by triggering letters the moment a new user joins a pipeline.
- Welcome letters
- Account credential mailers
- Service activation guides
- Membership tier upgrades
Human Resource Communications
Automate mandatory employee communication proactively to reduce administrative work for HR departments.
- Employment letters
- Employee termination notices
- Annual benefit enrollments
- Company policies
Claims & Coverage Notices
Implement robust claims processing and policy administration to reduce overhead costs, manual errors, and compliance risks.
- Claim approval/denial letters
- Policy lapse letters
- Proof of insurance requests
- Medical claims processing updates
Healthcare & Patient Management
Send critical patient correspondence with a HIPAA-compliant network. Verify mailing lists beforehand to ensure letters only reach the intended recipient.
- Appointment reminders
- Lab test results
- Patient discharge summaries
- Prescription refill notices
Why Use PostGrid for Sending Letters?
The only flexible solution for letters without any postal expertise.
Access to Virtual Mailbox
Digitize all incoming or return mail with high-quality OCR scanning and forwarding to overcome compliance challenges and operational overhead.
Global Carrier Routing
Ensure the fastest and cost-effective global delivery by routing letters via carriers like the USPS, Canada Post, Royal Mail, and Australia Post.
Full Creative Control
Complete flexibility to personalize letter templates with custom logos, fonts, colors, layouts, and other branding elements using the built-in, easy-to-use HTML template editor.
Customer Stories
With a 4.9-star rating, global organizations prefer PostGrid to print and send letters.
Read the Case Study
AtoB
The finance business was having a hard time scaling its time-sensitive welcome letters for new clients. They integrated PostGrid’s Letter API to witness a 40% improvement in operational agility.
Read the Case Study
EcoFlow
The global electronics manufacturer had a shortage of team members while managing its physical client communications. PostGrid helped with dynamic personalization, increasing website visitors by 20%.
Read the Case Study
Lumata Health
The healthcare provider was facing compliance difficulties while sending patient communication. PostGrid’s HIPAA-compliant API maintained data privacy and reduced distribution time by 50%.
Enterprise-Grade Compliance and Data Security
HIPAA
PIPEDA
GDPR
SOC 2 TYPE 2
PCI-DSS
Data Encryption
Audit Logs
Role-Based Access Control
Secure Hosting on AWS
Single Sign-On
Third-Party Penetration Testing
Continuous Monitoring
Integrates with Your Favorite Tech Stack & Tools
Easily Improve your workflow and automate print & mail through seamless integration capabilities.
Frequently Asked Questions
What Is the Turnaround Time for Printing and Mailing Letters With This API?
PostGrid offers an industry-leading 2-business-day Service Level Agreement (SLA). This timeframe includes processing, printing, and handing over letters to the postal carrier. The final delivery timeline depends on which mailing class an organization selects from PostGrid’s dashboard.
Are There Any Minimum Volume Requirements for Letters?
No, organizations can use the pay-per-piece model to avoid monthly commitments and continue to mail letters as per their requirements. However, high-volume mailing discounts are only available with the enterprise plan. For a complete price breakdown, please check out the pricing plans.
How Scalable is the Letter API?
PostGrid’s API can handle single-piece triggers or high-volume letters without any bottlenecks. The infrastructure relies on a vast network of printing partners across the world for scalable fulfillment.
Which Envelopes Are Used for Sending Letters?
Organizations can use #10 double window envelopes for all their standard letters. However, if the mailer has more than six pages, then it is automatically upgraded to a flat mailer.
Which Letter Sizes Does PostGrid Support?
The Letter API supports standard US Letter or Legal-sized documents.
Featured In
Media & Press
Ready to Get Started?
Start transforming and automating your offline communications with PostGrid
