Creditors can register preferred addresses with the Bankruptcy Noticing Center (BNC).
Mailing matrices are accessed from Utilities-Mailings:

List of Creditors. This list is accessed either from the Query menu or from Utilities-Mailings. Preferred addresses are displayed, undeliverable and duplicate addresses are noted, and PACER charges are incurred. When run in 3-column format, addresses submitted by the debtor for which the preferred address was substituted are also separately listed. This option lists creditors, debtors, any debtor’s attorney, the trustee, and the U.S. Trustee, but it does not include attorneys for other parties. This document may be printed onto Avery 5260 adhesive labels.

Mailing Matrix by Case. Use this option to ensure service on all parties and creditors. This option is available in ECF but not PACER, and is accessed from Utilities-Mailings. Preferred addresses are displayed, undeliverable and duplicate addresses are noted, and no PACER charges are incurred. If the default “All” is selected, all parties and creditors and their attorneys are included. It is also possible to narrow the label selection to certain parties, creditor committee members, only creditors who have filed claims, etc.