It's a reasonable worry: if a barcode fails to scan somewhere in a courier's network, does the parcel just get lost? In practice, no — but the fallback process is slower and less reliable than a clean scan, which is exactly why it's worth avoiding in the first place.
Manual keying and delays
Most courier depots have a manual override process where a staff member keys in a tracking number or address by hand when a scan fails. This works, but it's slower per parcel than an automated scan, and at a busy depot during peak periods it can mean a parcel sits in a manual-processing queue rather than moving straight through — adding a day or more to transit time in some cases.
Misrouting risk
Manual keying introduces human error in a way automated scanning doesn't — a mistyped digit in a postcode or tracking number can send a parcel to the wrong depot or delay its onward routing until the error is caught. This is rare, but it's a real risk that simply doesn't exist for a parcel that scans cleanly the first time.
Who's actually liable
If a scanning failure leads to a lost or significantly delayed parcel, liability generally sits with whoever's responsible for the label being unreadable — which in most cases traces back to a printing issue at the point of dispatch rather than anything the courier did wrong. This is one more reason it's worth testing barcode quality before shipping, covered in our scanning failures guide.
How couriers handle it in practice
Royal Mail and other major UK couriers are generally good at recovering from occasional scan failures — it happens often enough across their network that staff have well-practised manual processes. The real cost isn't usually a lost parcel; it's the accumulated delay and reduced tracking accuracy across many affected parcels if scan failures are a recurring problem rather than a one-off.
Reducing the odds it happens to you
Keeping print darkness correctly calibrated, using correctly-sized label stock, and avoiding print driver settings that rescale or crop labels (all covered in our driver mistakes guide) are the main levers within your control. The same applies to returns labels, which go through the same scanning process in reverse — see our guide to printing Royal Mail returns labels correctly.
Reliable scans start with reliable print
Our 4×6 direct thermal labels are tested for consistent contrast and barcode clarity across every roll.
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