Found by running system_tests, which masked email no longer stops:
- rcpt_resolve rewrites a live mask to its owner's address, so
Delivered-To names the account; delivery recognizes the mask from the
original recipient when it belongs to that account.
- x:MaskedEmail/set create responses carry the server-set email.
- x:MaskedEmail/query returns every mask to a server-level impersonate
holder, and filters on accountId.
- The refusal for an unlinked emailDomain uses upstream's wording.
- The shared delivery test checks the fork's address format (ME-13).
- The masked email test's tenant domain uses manual DKIM, so its cleanup
leaves nothing behind.
jcoffey-dev