diff --git a/features/masked-email.md b/features/masked-email.md
index aed0366..8fa5c11 100644
--- a/features/masked-email.md
+++ b/features/masked-email.md
@@ -290,5 +290,12 @@ deleted, and nothing was left. No upstream code was read.
 7. **Permissions.** The ordinary account holds all five `sysMaskedEmail*`
    permissions.
 
-Not settled: 8, how many masks INBUXA holds across all accounts. It needs
-admin rights or the operator's count, and only sizes the compatibility test.
+8. **How many masks INBUXA holds.** Operator's estimate, 2026-09-18: fewer
+   than 20 special addresses in all, 7 on the operator's own account and the
+   rest postmaster addresses. Those may be ordinary account aliases rather
+   than masks. Aliases carry over unchanged and aren't part of this feature.
+   If none are masks, the compatibility test (acceptance 12) has no existing
+   masks to carry over, and instead checks that upstream-shaped addresses
+   created on a copy before cutover still deliver after it. Count masks
+   exactly (`x:MaskedEmail/query` as an admin) during the cutover dry run
+   (SPEC.md §7).