- Deliverability is earned infrastructure: authentication, warm-up, verification, moderation.
- Keep bounces under 3% and cold volume under ~50/inbox/day.
- Use a separate sending domain — never risk your main company domain.
You can write the best cold email of your career, and it dies silently in a spam folder — no bounce, no warning, just zero replies from a hundred sends. Deliverability is the invisible foundation under every outreach program, and it obeys rules that are unforgiving but learnable.
Authentication: the entry fee
SPF, DKIM, and DMARC are DNS records proving your mail is really from you. Since Google and Microsoft tightened bulk-sender rules, missing authentication doesn't just hurt — it's disqualifying. Set all three on your sending domain, verify with a testing tool, and while you're there: use a separate domain for cold outreach (yourcompany-hq.com, getyourcompany.com) so your primary domain's reputation is never on the line. It's cheap insurance every serious team buys.
Warm up before you rev up
A new domain or inbox that starts blasting 200 emails on day one looks exactly like a spammer, because that's exactly what spammers do. Warm up over 3–4 weeks: start at 10–20 emails a day, grow gradually, accumulate genuine positive engagement. Then hold steady-state cold volume around 30–50 per inbox per day, scaling with more inboxes rather than more volume per inbox. Spiky, greedy sending patterns trip filters that smooth ones glide past.
Verify every address, every time
Hard bounces are reputation poison — sustained bounce rates above 2–3% mark you as a careless sender for months. The fix is mechanical: verify at list-build AND again at send time, since addresses die between the two. Strip catch-alls and role accounts (info@, admin@). This is why verification is built directly into BixJet's email finder — addresses are checked before they ever enter a sequence.
Content and behavior signals
- Plain-text-looking emails outperform designed HTML for cold outreach — and deliver better
- One link maximum, no attachments, no tracking-pixel-heavy templates
- Vary your sending times and message bodies; identical mass-blasts fingerprint easily
- Prune non-engagers after the sequence ends — mailing the dead hurts the living
If you're already in spam
Cut volume to a trickle, mail only your most engaged addresses (replies beget reputation), fix whatever broke — usually bounces or a missing DMARC — and rebuild over 2–3 weeks. Recovery is slower than prevention; that asymmetry is the whole argument for doing this right from day one.