Plans a Maildir mailbox source, a containerized SMTP/IMAP test server,
deterministic test-user mailboxes, and end-to-end send-and-scan integration
tests, so automated test environments get mail accounts for test users without
a live provider.
Records the decision to use a purpose-built test server rather than integrating
s/qmail, and keeps bounce/complaint/deferral evidence on fixtures plus an
optional provider simulator tier.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
