# A correct map pin can still be the wrong delivery address

Separate physical location, postal destination and service instructions. One address field cannot reliably carry all three meanings.

By Cobnex editorial. Published 2026-09-10. Updated 2026-09-11.

## Ask what the address is for

A maintenance customer may receive invoices at a PO Box, operate from a workshop and need technicians to enter through a gate on another street. These are related pieces of information, but substituting one for another creates different failures.

Model the purpose explicitly. The billing contact needs a postal destination. Dispatch needs a service location and access instructions. A courier integration needs an address compatible with its delivery service. Do not make every workflow inherit a single customer address because that is convenient for the database.

Australia Post documents postal addressing, including PO Boxes and Locked Bags. G-NAF is a physical address reference. A match in a physical address dataset should not be presented as proof of postal deliverability or permission to enter a property.

## Preserve what the user selected and what they supplied

An autocomplete result can improve consistency, but it is still a candidate. Store its provider identifier and relevant components alongside the user's confirmed address. Preserve meaningful additions such as a unit, building or delivery instruction in their proper fields.

If the user changes the selected street number, the old provider match may no longer apply. Clear or revalidate the association rather than keeping a reassuring Verified label attached to a different address.

### Address evidence stays separate from business purpose

The application records the intended use, assists entry and confirms the appropriate destination before downstream work begins.

1. **Purpose**: Choose postal, service or another explicit role
2. **User entry**: Capture components and allow a manual path
3. **Reference match**: Store candidate identity, source and review state
4. **Workflow use**: Render the correct label or service destination

## Keep identifiers out of numeric arithmetic

A postcode is an identifier, not a quantity. Store it as text so a leading zero survives forms, spreadsheets and API calls. The same principle applies to unit and street components that may contain letters or ranges.

Avoid a validation rule that accepts only an integer street number. It can reject legitimate forms of address before a person can explain them. Use purpose-appropriate components and an escape path for cases the reference service does not recognise.

A postcode and suburb combination is useful validation evidence, but it does not identify a particular premises. Likewise, several units can share a building coordinate. Geospatial proximity alone is a poor basis for merging customer records.

## Make correction a versioned business change

When a customer moves, update the relevant current address and decide which future activities should use it. Preserve the destination recorded on an already dispatched job or issued document where that history is needed.

An illustrative failure is a support agent correcting a customer's billing address and unintentionally moving tomorrow's site visit to the accountant's office. Separate address roles and an impact preview prevent that mistake more effectively than another regular expression.

## Decide how an unmatched address proceeds

New developments, unusual premises and incomplete reference data need a supported path. Let users enter an address manually and label its review state accurately. If a particular delivery service cannot use it, explain that restriction at the service decision rather than claiming the address does not exist.

The design should make uncertainty visible without trapping the customer. A useful record answers what the address is for, who confirmed it, which evidence supports it and what remains unresolved.

## Sources

- [Australia Post: addressing guidelines](https://auspost.com.au/personal/sending/sending-guidelines/addressing-guidelines)
- [Australian Government: G-NAF and administrative boundaries](https://www.industry.gov.au/publications/geocoded-national-address-file-g-naf-and-administrative-boundaries-ab-data)