All transactional/worker senders built multipart/alternative (or mixed)
messages with ONLY an HTML part. A single-part multipart/alternative is
malformed and HTML-only mail is a spam-score signal -- the same class of
deliverability bug that hurt the campaign pipeline, but on the telecom /
filing / customer-transactional path (499-Q reminders, RMD/FCC filing
review links, intake/completion/delivery emails, commissions, etc).
- worker_email.send_worker_email: auto-derive plaintext from HTML when
caller omits text= (fixes the shared helper for all current+future use)
- 16 rolled-their-own senders in scripts/workers/** + scripts/formation/
document_delivery.py: attach html_to_text(...) plaintext sibling before
the HTML part (job_server + document_delivery wrap text+html in an
alternative sub-part so PDFs still attach to the mixed root)
- api/src/email.ts: add dependency-free htmlToText() and default
sendEmail text to it (fixes checkout/webhook HTML-only sends)
Verified: all py files compile + import at runtime, api tsc passes,
htmlToText handles hrefs/lists/entities, 11 plaintext unit tests pass.
Telecom campaign 407 (Jun 8) was HTML-only + sent in the DKIM-broken
window -> 384 sent / 0 clicks (same junked-mail signature).
