Sending subdomain vs root domain: pick correctly

Sending subdomain vs root domain: pick correctly
A frame: this one quietly decides whether one bad campaign can poison your whole brand. The best reads make the stakes clear.

🚀 Deliverability
— Sender-domain isolation guide — made the cut for the core move: send marketing from mail.brand.com so a promo blacklist never touches brand.com email.
— DMARC-alignment note — worth your time because it explains why the subdomain must still align to pass, not just exist.

🧪 Tests
— Reputation-inheritance study — picked it for the nuance: a fresh subdomain doesn't fully inherit root reputation, so you still warm it.

📥 Swipe
— Multi-subdomain strategy (promo / txn / cold) — earned its spot for the clean separation serious senders use.

Takeaway: never send affiliate promos from your root. Isolate, align, warm.
Saved you ~2 hours.