We're making a small change to the API on the "Customer lookup" API endpoint (/customers/lookup?reference=12345). We have always explicitly expected URL-encoded values for the reference id (which could be a number or a string). However, on our end, we were double-decoding these values. For numbers it doesn't matter. And most other strings worked fine. Even "joe%40example.com" worked because "@" decoded remains "@".
However, more complex strings, like "joe%2Bschmoe%40example.com" Don't work because the "+" gets decoded to me " " (blank space). We are now fixing this so that e-mail address lookups in the reference field work correctly.
If you were counting on our broken behavior and were double encoding your reference lookup, it will no longer work. Please just single URL-encode the search string from now on. We've searched our logs and don't believe there will be anyone affected, but just in case, are posting the notice here.