Getting to the inbox has never been harder. Gmail, Yahoo and Microsoft now enforce rules that used to be optional. Here's what matters, in the order we'd fix it.
1. Authenticate your domain
Inbox providers want proof that your emails really come from you. That proof is three DNS records:
- SPF lists the servers allowed to send for your domain.
- DKIM adds a digital signature to every email.
- DMARC tells inbox providers what to do when SPF or DKIM fails, and sends you reports.
Since 2024, Gmail and Yahoo require all three for anyone sending more than 5,000 emails a day to their users. Microsoft followed for Outlook.com in 2025. Even if you send less, set them up. It's the single biggest deliverability fix.
p=none to collect reports, fix anything failing, then move to quarantine or reject.2. Make unsubscribing easy
Bulk senders must support one-click unsubscribe and honour requests within 2 days. In Canada, CASL already requires a working unsubscribe in every commercial email. A hidden unsubscribe link doesn't keep people on your list. It just gets you marked as spam.
3. Keep spam complaints under 0.3%
Gmail's limit is a 0.3% spam rate, and the healthy target is under 0.1%. Watch it in Google Postmaster Tools. If it climbs, look at who you're sending to and how often.
4. Clean your list, and have a sunset policy
Sending to people who never open hurts your reputation for everyone else on the list. A sunset policy fixes that:
- Flag subscribers with no opens or clicks in 6 months.
- Send them a short re-engagement series.
- Stop emailing anyone who still doesn't respond.
Your list gets smaller. Your open rates, inbox placement and revenue per email go up.
5. Segment, don't blast
One newsletter to everyone is the fastest way to lose attention. Segment by what people bought, what they clicked and where they are in the customer lifecycle. Even three segments beat one.
6. Automate the moments that matter
The highest-performing emails are triggered by something the customer did. Start with these:
- Welcome series for new subscribers
- Onboarding for new customers
- Abandoned cart or abandoned form
- Win-back for lapsed customers
7. Write for a phone screen
- Subject lines under about 45 characters
- One main message and one clear button per email
- Real text, not text inside images
- Alt text on every image
- A plain-text version
8. Test, then test again
Test one thing at a time, like the subject line, offer or send time, on a big enough sample to trust the result. Then keep the winner and test the next thing.
Sender rules change. Check the current requirements from Google, Yahoo and Microsoft before making changes to your set-up.