10 deliverability strategies
that actually move the needle
A message in spam is a dead message. Doesn't matter how good your copywriter is or how clean the design looks. If Gmail has decided you're a spammer, you're a spammer.
These are 10 things that, in our experience, actually shift deliverability. Not textbook theory — things we've verified on real sending campaigns for uChecker clients.
SPF, DKIM, DMARC — set them up once and stop worrying
Three DNS records. Ten minutes of work. After that, mail providers stop looking at you sideways. SPF says "these are my sending servers," DKIM cryptographically signs every message, DMARC sets the rules for what happens to spoofed mail.
Gmail has rejected messages from domains without DMARC since February 2024. Yahoo too. Other providers are moving the same direction.
Start with p=none, watch the aggregate reports for a couple of weeks, then switch to p=quarantine. Very few senders reach p=reject, but that's where the real protection is.
Authentication covered. Now for the tedious part: warm-up.
Domain and IP warm-up
A new domain is like a new social media account: zero reputation. Send 50,000 messages on day one and providers will assume you bought a list. In 90% of cases they'd be right.
Warm-up means 200 messages on day one, 400 on day two, 800 on day three. You send to your most engaged subscribers first — the ones who will actually open. Their opens and clicks build your sender reputation. Two to four weeks, then you can scale up. Boring? Yes. But the alternative is landing on the Spamhaus blocklist by day two.
Validate your list before every send
Hard bounce above 2% is a red flag. Above 5% and you're already on a blocklist. The problem is that addresses die quietly: someone leaves a job, a company shuts down, a free mailbox gets abandoned.
Our data shows lists lose 20–25% of valid addresses per year. A quarter of your list. If you haven't validated in 12 months, one in four messages is going nowhere.
Validating before every large campaign is the minimum. Quarterly for the full list is the standard.
What if the addresses are correct, but the subscribers are fake?
Double opt-in
Someone enters their email, gets a confirmation message, clicks the link, lands on your list. Two steps instead of one. Yes, signup conversion drops 20–30%. That's the best thing that can happen to your list.
Because the 70% who remain are real people who genuinely want your messages. They won't hit spam. They won't forget they subscribed. Bots and typos get filtered out at step one.
Bounce rate is your main diagnostic
Hard bounce means the address is dead — remove it immediately. Soft bounce means the mailbox is full or the server is down — try three times, then archive it.
Simple rule: bounce rate above 3% on a single campaign means stop. Not "let's watch next time" — stop right now. Dig into the cause: stale segment, bad import, broken CRM integration.
Set up alerts in your ESP. Automated monitoring catches problems faster than you'll spot them in the dashboard.
Technical side sorted. Now for content and engagement behavior.
Segment. Seriously.
One blast to your whole list is shouting into a megaphone in a crowded square. A few people listen; most look away.
New subscribers
Welcome sequence of 3–4 messages. Introduce the product, give something useful.
Active subscribers
Personalized offers, early access, upsell. They already trust you.
Dormant subscribers
Re-engage or remove. Keeping them on your list hurts your reputation.
Gmail tracks open rates and clicks per sending domain. Segments that consistently engage push your messages into the inbox. Segments that don't push you toward Promotions — or worse.
Frequency: not too much, not too little
E-commerce: 2–4 per week. B2B: 1–2 per week. Digests: once a week or two. The real lever is asking subscribers. A preference center where people set their own cadence cuts unsubscribes by 2–3x.
When someone chooses "once a week" themselves, they won't complain about spam.
Now the message itself. What's inside also affects deliverability.
Content: 60% text, 40% images
A message that's one big image is a red flag for filters. That's how spammers send. Add text — actual meaningful text, not a wall of keywords.
"FREE!!!" in the subject line sends you straight to spam. All caps, three exclamation marks, "URGENT OFFER" — all triggers. Filters are smarter now, but the basics haven't changed.
Always include a plain-text version. Some clients show only that, and its absence is its own spam signal.
Sunset policy — remove the dead weight
A subscriber hasn't opened anything in 9 months. You keep sending. Why? Every unopened message is a hit to your domain reputation. Mail providers measure engagement, not list size.
Before removing, try re-engagement: 2–3 messages with a direct question, "Do you want to stay?" No response means archive. No regrets.
It's psychologically hard to cut a list you paid to build. Think of it as an investment, not a loss.
Last one — infrastructure.
Your ESP matters too
On a shared IP you share reputation with hundreds of other senders on the same platform. One bad neighbor and your messages take the hit. Dedicated IPs fix that, but they require volume: at least 50,000 messages per month, otherwise you won't build enough reputation to matter.
When picking an ESP, look for: strict anti-spam enforcement (a good sign, not a bad one), deliverability monitoring tools, postmaster feedback loop support, and documentation that actually makes sense.
Postmark for transactional mail. Amazon SES if you need low cost and full control. Mailgun sits in the middle. For high-volume bulk sending, check whether your ESP has a feedback loop agreement with major inbox providers.
Where to start?
List validation is the fastest way to improve deliverability. Takes minutes, and the effect shows up on the very next campaign.
Validate your list with uChecker →