Call out two facts that already caused a confusing failure, before the
build phases begin:
1. Force IPv4 for every Gmail connection (IMAP and SMTP).
2. The source address header is X-Pm-Original-To; never use Delivered-To.
Additive only. No FR id, phase id, or other section is changed.
Co-Authored-By: Paperclip <noreply@paperclip.ing>