Cannot Sort Mailing Labels by Postal Code

Mailing Labels cannot be sorted by postal code when using "All xxx Records". I classified this as a bug because in the United States, the postal service requires bulk mail to be sorted by postal code.

Steps to reproduce:

1) Run a search (any criteria is fine so long as postal code is displayed)
2) Sort results by Postal Code
3) Tick "All xxx Results" (where 'xxx' is the number of results.)
4) Under "More Actions", select "Mailing Labels"
5) Proceed to create mailing labels (any type is fine)
6) Labels are sorted by last name regardless of sort order of search results.

One proposed workaround was to use "Selected records only" but this presents two major problems:

1) User must repeat the steps several times if search has returned more than 100 records.
2) This wastes labels since the search results are displayed in amounts that aren't divisible by the number of labels per sheet.

I would propose a "Sort by Postal Code" checkbox on the label creation page, perhaps under the "Combine same address" option.