USPS "service not available" from a rule that rewrites Ship To

Summary: If USPS returns "service not available" on one profile even though the destination looks fine, a business rule may be rewriting the Ship To address before rating. Find the rule and fix it so it sets only the field it should.

Problem

An order fails to rate on USPS for one profile with:

service not available

The destination address on the order looks valid, but rating still fails, and the failure follows the profile, not the order.

Cause

A global business rule is overwriting the Ship To address before the rate call. A common cause is a return-address rule with the wrong action: instead of setting the Return To address, it sets the Ship To address to your own address. With the destination replaced, USPS has no valid ship-to for the service and returns "service not available." Sometimes there are two rules with the same name, and one of them has the wrong action.

How to check: open the profile's business rules and look for any rule whose action sets an address. If a rule sets Ship To (not Return To), that is the cause.

Fix

Open the profile's global business rules and list any rule whose action sets an address (Return To or Ship To).
Find the rule that changes the Ship To address, and any duplicate rules with the same name.
Fix the rule so it sets only the field it should. A return-address rule should set Return To, not Ship To.
Remove any duplicate rule that overwrites Ship To.
Re-rate the order and confirm USPS is now available.

What you should see

The order rates and ships on USPS with no "service not available" error, and the Ship To on the shipment matches the order's destination.

The wrong Return To address prints when a rule fires

Knowledge Base