By
Lob
Direct mail routing is the system that determines how your postcards, letters, and catalogs travel from a print facility through the USPS network to each recipient's mailbox. It's the logistics backbone of every direct mail campaign, and it directly affects how fast your mail arrives, how much you pay in postage, and whether your timing hits the mark.
Most marketers focus on creative and targeting, but routing decisions can make or break campaign performance. This guide covers how mail processing works, the different routing methods available, and how to optimize for speed, cost, and deliverability.
Direct mail routing is the process that determines how your mail travels from a print facility to each recipient's mailbox. Think of it as the GPS for your postcards and letters. Routing determines which USPS sorting centers your mail passes through, how it gets organized along the way, and when it arrives in each recipient's mailbox. This is different from your direct mail marketing strategy. Routing is purely about the logistics of moving physical mail from point A to point B.
Why does routing matter to you as a marketer? Because it directly affects three things you care about: how fast your mail arrives, how much you pay in postage, and whether your campaign hits mailboxes when you planned. Better routing means faster delivery, lower costs, and more predictable timing.
Every piece of mail follows a specific journey from printer to mailbox. Understanding each stage helps you see where delays happen and where you can save money.
Before your mail even enters the USPS system, it goes through preparation. Presorting is the big one here. This means grouping mail by ZIP code so USPS has less work to do. In exchange for doing this sorting upfront, you get lower postage rates.
Address validation also happens at this stage through something called CASS certification (Coding Accuracy Support System). CASS checks that every address on your list is real and deliverable. Bad addresses waste money and hurt your sender reputation.
At Lob, we handle both presorting and address verification automatically. You upload your list, and our system takes care of the rest before anything prints.
Once mail enters the postal network, it moves through a hierarchy of facilities. Network Distribution Centers (NDCs) handle the first round of sorting for large regions. From there, mail flows to Sectional Center Facilities (SCFs), which sort for specific geographic areas. Finally, local post offices take over for the last leg.
At each stop, the Intelligent Mail Barcode (IMb) on your mail piece gets scanned. The IMb is a long barcode printed on every piece of commercial mail. It's what makes tracking possible. Without it, you'd have no idea where your mail is or when it might arrive.
The final stretch takes mail from local post offices to individual mailboxes. How long this takes depends on two main factors: the mail class you chose (First-Class moves faster than Marketing Mail) and how far the mail traveled to get there.
Rural routes typically take longer than urban deliveries. And if your mail entered the postal system far from its destination, add extra days to your timeline.
The routing method you pick depends on whether you're targeting specific people or blanketing entire neighborhoods. Each approach has trade-offs.
Every Door Direct Mail (EDDM) is a USPS program that delivers to every address along selected carrier routes, no mailing list required. You pick neighborhoods based on demographics like age, income, or household size, and USPS handles the rest.
EDDM works well for local businesses, grand openings, or any campaign where geographic coverage matters more than individual targeting. The trade-off? You can't personalize, and you can't track individual pieces.
Addressed mail uses a curated mailing list to reach specific people. You control exactly who gets your message, and you can personalize each piece with the recipient's name, past purchase history, or tailored offers.
This method also gives you better tracking since each piece has a unique barcode tied to a specific recipient. For acquisition or retention campaigns where precision matters, addressed mail typically delivers stronger results.
First-Class is your go-to for urgent communications. Undeliverable pieces get returned to you with the reason why. Marketing Mail costs less but takes longer, and undeliverable pieces get discarded rather than returned.
Optimized routing isn't just a logistics detail. It directly affects your campaign performance and budget.
Clean addresses and proper routing reduce the number of pieces that bounce back as undeliverable. Address verification catches errors before mail prints, saving you money on wasted postage and printing costs.
Strategic routing shortens transit time. One technique called drop shipping transports mail to a facility near the recipient's area before it enters the postal system. This approach can shave days off delivery windows for time-sensitive campaigns.
USPS offers volume-based discounts for presorted mail. The more work you do upfront to organize mail by ZIP code, the less you pay per piece. Automation rates, available for mail that meets specific formatting and barcoding requirements, provide additional savings.
Modern routing includes scan-based tracking through Intelligent Mail Barcodes. You can monitor each piece through delivery and connect that data to your campaign analytics. This visibility lets you measure direct mail with the same precision you apply to digital channels.
Several variables influence whether your mail arrives on time and intact.
CASS certification is the USPS standard for address validation. Running your list through CASS-certified software before mailing catches typos, outdated addresses, and formatting errors. Accurate addresses mean successful delivery. Bad addresses mean wasted spend.
Minimum volume thresholds apply for presort discounts. You typically need at least 200 pieces for basic rates and 500+ pieces for deeper discounts. Higher volumes unlock better rates and more routing options.
Closer destinations equal faster delivery. Where your mail enters the postal system affects transit time, which is why distributed printing networks can speed things up. They produce mail closer to recipients rather than shipping everything from one central location.
USPS has specific size and weight requirements that affect both routing and cost. Non-standard pieces, oversized postcards, unusual shapes, or heavy items, may face delays or surcharges. Sticking to standard formats keeps things moving smoothly.
Your mailing list is the foundation of any direct mail program. List quality directly impacts routing efficiency and campaign results.
Your CRM and transaction data provide the most accurate, permission-based lists available. Your existing customers already know your brand, making them more likely to respond. Integrating your CRM with your direct mail platform keeps data fresh and enables triggered campaigns based on customer behavior.
For acquisition campaigns, data providers offer lists segmented by demographics, interests, or behaviors. Quality varies widely between providers, so vetting your sources matters. Bad data means wasted postage and poor deliverability.
Regular list cleaning removes outdated addresses, duplicates, and undeliverable records. The USPS National Change of Address (NCOA) database helps identify people who've moved. Clean lists improve routing efficiency and reduce waste.
Understanding pricing helps you budget accurately and spot opportunities to reduce costs.
Marketing Mail offers the lowest rates for bulk promotional mailings. First-Class costs more but delivers faster. Rates vary by weight, format, and whether you're sending letters, postcards, or flats (larger flat pieces like catalogs).
Presorting by ZIP code earns postage discounts because you're doing work USPS would otherwise handle. Automation rates, available for mail with proper barcoding and formatting, offer additional savings of several cents per piece. On high-volume campaigns, those cents add up fast.
Juggling multiple vendors for design, printing, and mailing adds overhead that doesn't show up in your postage line item. Handoff delays, miscommunication, and duplicate work all cost time and money. Consolidating with a single platform reduces friction and often lowers total campaign costs.
Visibility into delivery status closes the gap between sending mail and measuring results.
The IMb is a scannable barcode printed on each mail piece that enables piece-level tracking through the USPS network. Every scan creates a data point you can use to monitor progress from facility to facility.
At Lob, we surface tracking events as they happen, so you know exactly when mail arrives rather than guessing based on averages. This visibility helps you time follow-up communications and measure true delivery windows.
Link delivery data to response tracking through QR codes, personalized URLs (PURLs), or unique promo codes. This connection lets you attribute conversions to specific mail pieces and calculate true ROI, the same way you measure digital campaigns.
Routing complexity is one of the biggest barriers to scaling direct mail. Automation removes that friction by handling preparation, optimization, and tracking in one place.
Modern platforms like Lob manage the entire workflow, from address verification to presort optimization to real-time tracking, without manual intervention. Our Print Delivery Network produces mail at facilities across the country, automatically routing each piece through the optimal path for speed and cost. Routing intelligence like Postal IQ helps determine the best path and entry strategy before mail moves through the network.
The result? Direct mail that works like your digital campaigns, fast, flexible, measurable, and scalable.
Ready to see how Lob automates direct mail routing? Book a demo
FAQs about direct mail routing
FAQs
How long does direct mail routing take from send to delivery?
First-Class Mail typically arrives within 1-5 business days. USPS Marketing Mail takes 3-10 business days depending on distance and volume. Actual delivery windows vary based on entry point, destination, and current postal capacity.
Can you route direct mail to international addresses?
Yes, though international mail involves customs processing, longer transit times, and higher costs. Most direct mail marketing campaigns focus on domestic delivery where routing is more predictable and cost-effective.
What happens when a mail piece is undeliverable?
First-Class Mail gets returned to sender with the reason for non-delivery. Marketing Mail is typically discarded rather than returned, which is why address accuracy matters even more for promotional campaigns.
How is direct mail routing different from regular personal mail?
Commercial direct mail uses presort processing, barcoding, and bulk entry points to reduce costs. You're essentially doing work that earns postal discounts. Personal mail goes through standard USPS handling at full retail rates.
Should you use EDDM or addressed mail for your campaign?
EDDM works best for local saturation when you want to reach everyone in a geographic area without maintaining a list. Addressed mail is better when you want personalization, precise targeting, and piece-level tracking for specific recipients.
Answered by:
.png)