v2.17.8

Fixed

• SMTP replies and forwards now read composite imap: IDs directly from their
  encoded account/mailbox/UID instead of passing them to a numeric AppleScript
  source lookup. This prevents the clean SMTP path from falling back merely
  because IMAP supplied the id. Reads are bounded to 25 MiB and release the
  mailbox lock on success and failure. Decoded IMAP subjects are preserved.
• Reply routing has executable regression coverage, including rendered MIME:
  the new body stays unquoted and the original thread headers reach SMTP.
• SMTP forwards reject originals without a readable plain-text body, including
  HTML-only IMAP messages and failed Mail.app body reads, instead of silently
  dropping the original content. Explicit AppleScript forwarding remains available.

Changed

• Replies and forwards accept an explicit smtp/applescript transport and
  report the selected transport (plus the SMTP message id when available).
  Breaking failure behavior: once SMTP is selected, configuration/source
  failures, missing reply headers, and send failures are returned rather than
  silently falling back to AppleScript. Explicit AppleScript remains available;
  omitted transport still uses it when SMTP is unconfigured or saving a draft.
  SMTP with send: false is rejected before composing.
• The newly enabled IMAP-to-SMTP compose route rejects unrelated source-account
  identities. The IMAP login must match the SMTP login, From, or an explicitly
  configured allowed identity. Configured aliases are excluded from reply-all.