Old-school lore says a P.S. lifts response 8-12% in sales letters; in email campaigns I’m getting higher CTR with a P.S. but more spam flags and lower deliverability. Keep it for clicks or cut it for inboxing?
If it’s hurting deliverability, cut it in cold sends and keep it only for warmed/engaged segments. When you do use it, make it a single plain‑text line under the sig with one branded link (no UTMs/redirects) and A/B it against no P.S. while watching seed inboxing and complaint rate in Postmaster/Seedlist for a week.