About 15% of marketing email never reaches the inbox. The three DNS records now required of bulk senders, the complaint ceiling that actually applies, and why the Promotions tab is not failure.
Cyril Nie
Author
About 15% of all marketing email never reaches the inbox at all. Deliverability is the invisible tax on everything else you do. The good news: most of it comes down to three habits.
SPF, DKIM, and DMARC are three DNS settings that act like an ID card for your email. Without them, you’re a stranger — and strangers go to spam. Since February 2024, Google and Yahoo require them for bulk senders, plus complaints under 0.3% and bounces under 2%. Setting them up right can lift delivery by 5–10%. If your list is over 5,000, use a branded sending domain.
Most deliverability problems are list problems in disguise. Remove addresses that bounce. Stop sending to people who’ve been quiet for months (see Chapter 4’s tiers). Never buy lists. Inbox providers watch how people react to you: when engaged people open and click, your reputation climbs; when ignored people delete without reading, it sinks — for everyone on your list.
Spam complaints above 0.3% get you throttled by Google and Yahoo. One bad send can take weeks to undo. Keep complaints under 0.1%, and check Google Postmaster Tools (it’s free) to see your domain reputation.
Landing in Gmail’s Promotions tab is not failure. It means Gmail sees you as a legit business sender — which is correct. People checking Promotions are in a buying mood; some tests show higher conversion there. If you still want Primary: ask people to reply (the strongest signal), ask them to drag your first email over, use a personal from-name, and go lighter on images. But don’t obsess. Plenty of brands make millions from the Promotions tab.
Never send cold outreach from your marketing domain. Cold email needs its own separate domain and tools. Mix them and you risk your ESP banning you and your main domain getting blacklisted — killing every email you send.
If you do send cold email, judge it by a different number. Ignore opens. Count good replies. 3–5% means your list, your subject line, and your offer are all working. Under 1% means something basic is broken. Check bounces and complaints every day, because cold sending goes bad fast when your addresses are old.
Three DNS records that prove an email genuinely came from your domain. SPF lists which servers may send for you, DKIM cryptographically signs each message, and DMARC tells receivers what to do when a message fails. Google and Yahoo have required all three from bulk senders since February 2024.
Keep it below 0.1 percent. Google treats 0.3 percent as the threshold where filtering starts, and reputation damage takes weeks to repair even after the cause is fixed. One complaint per thousand delivered is the working ceiling.
Yes. Addresses that have not opened or clicked in six to twelve months depress your engagement signals, which is one of the strongest inputs into inbox placement. Try a reactivation sequence first, then remove the people who do not respond.
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