What Is Intelligent Mail Barcode (IMb) and How Does It Work?

By Lee Garvey

If you’ve looked closely at a piece of business mail recently, you’ve likely noticed a row of tall and short bars printed near the address area. That’s the Intelligent Mail Barcode, and it carries significantly more information than it appears to. For businesses that send mail at any volume, understanding how IMb works — and what it makes possible — changes how you think about mail tracking, delivery timing, and campaign coordination.

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What Is the Intelligent Mail Barcode?

The Intelligent Mail Barcode, commonly referred to as IMb, is a 65-bar barcode developed by the USPS to track and sort mail pieces throughout the postal network. It replaced two older barcode systems — the POSTNET barcode and the PLANET Code — combining their functions into a single, more capable standard.

Each IMb encodes up to 31 digits of data, including:

• A barcode identifier
• A service type code indicating the mail class and special services
• A mailer identifier linking the piece to the sending organization
• A serial number unique to each individual mailpiece
• The destination ZIP code

That last point is worth emphasizing: every single mailpiece gets its own unique serial number. This is what makes individual piece tracking possible, as opposed to the older system where tracking was limited to bulk batches.

The USPS provides detailed technical specifications for the Intelligent Mail Barcode for mailers and developers who need to work with the standard directly.

How IMb Tracking Works

As a mailpiece moves through the postal system, the IMb is scanned at multiple points along the way. Each scan creates a record that includes the location, the time, and the status of the piece. Those records are aggregated into the USPS tracking database and made available to senders in near real time.

The journey of a typical tracked mailpiece generates scans at several stages:

• Acceptance — when the piece enters the postal system at a processing facility
• In transit — as it moves between sorting facilities en route to its destination
• Out for delivery — when it’s loaded onto a carrier’s route
• Delivered — when it reaches the recipient’s address

For businesses using Click2Mail, this scan data is automatically captured and returned through the platform. You don’t need to check the USPS website manually — the tracking information comes back to you as part of your mailing record.

IMb vs Standard Package Tracking

A common point of confusion is the difference between IMb tracking on letter mail and the tracking most people are familiar with from package shipping. They work on the same general principle but with some important differences.

Package tracking on Priority Mail and Priority Mail Express is highly granular, with frequent scans and near-guaranteed delivery confirmation at the piece level. IMb tracking on standard First Class Mail and marketing mail is less granular — not every piece gets scanned at every stage, and delivery confirmation is not always captured for every mailpiece.

That said, IMb tracking on First Class Mail still provides meaningful data, particularly at the campaign level. When you’re mailing thousands of pieces, the aggregate scan data tells you when your campaign is reaching mailboxes — which is exactly what you need to coordinate follow-up outreach across channels.

Why IMb Matters for Business Mailers

Delivery Timing and Campaign Coordination

Knowing when your mail is arriving lets you synchronize other marketing and sales activities around it. As Click2Mail CEO Lee Garvey explains: “You want them to get a phone call at the same time they get mail in the mailbox, and emails should arrive as the mail piece gets in the mailbox. You can’t do that normally — but with Click2Mail, we give you the data coming back from the postal service so you can do it automatically.”

This kind of multi-channel timing is one of the most effective ways to increase response rates, and it’s only possible with reliable delivery data.

Operational Planning

For businesses sending invoices, statements, or time-sensitive notices, knowing when mail is arriving at recipients’ local post offices allows customer service teams to anticipate incoming calls and questions. Carly Brown, Click2Mail’s customer support manager, describes the operational value: “If you know that all of your direct marketing pieces have arrived at the recipients’ post office, you can anticipate getting a bunch of phone calls the next day — it gives you extra planning abilities.”

Compliance Documentation

For regulated industries, IMb scan data contributes to the audit trail that proves a notice was mailed and when. Combined with Certified Mail tracking and a Return Receipt, it creates a complete delivery record that holds up in legal and regulatory proceedings.

Postage Discounts

Using IMb-compliant barcodes qualifies mailers for automation postage discounts from the USPS. Pieces that meet USPS automation compatibility standards — correct barcode placement, address formatting, and clear zone compliance — receive lower postage rates than non-automated mail. Click2Mail applies CASS-certified address processing and IMb encoding automatically, so every mailing qualifies for available discounts without any additional steps from the sender.

IMb and Address Quality

The IMb doesn’t just track mail — it’s also part of the USPS address correction and forwarding system. Service type codes embedded in the barcode tell postal carriers what to do with a piece if the recipient has moved or the address is undeliverable. Options include forwarding the piece, returning it to the sender, or notifying the sender of the new address electronically.

This is one reason address quality matters so much before a mailing goes out. An accurate address means the IMb works as intended. A bad address means the piece may be returned, forwarded to an unknown location, or simply discarded — with the tracking data reflecting that outcome and nothing more.

Click2Mail applies automatic NCOA (National Change of Address) processing to all mailings, cross-referencing recipient addresses against the USPS change of address database before pieces go to print. This catches outdated addresses before they become wasted postage.

How to Get IMb Tracking on Your Mailings

For businesses sending mail through Click2Mail, IMb tracking is included automatically on every mailpiece at no additional cost. There’s no separate enrollment, no barcode to generate manually, and no additional setup required. The barcode is applied during production, the scan data is captured as the piece moves through the postal network, and the delivery information feeds back into your mailing records automatically.

Physical mail has always had a delivery problem — not in actually getting there, but in knowing when it got there. The Intelligent Mail Barcode solves that problem, turning every piece of outgoing mail into a trackable, data-generating asset. Visit Click2Mail.com to start sending tracked mail without any additional setup or cost.