How to keep your emails out of the spam folder

Deliverability is whether your email reaches the inbox rather than the spam folder, or doesn’t arrive at all. It is decided by the inbox providers (Gmail, Outlook, Yahoo, Apple and others), and they mostly judge three things: who you are, how people react to your email, and how clean your list is.

1. Prove who you are: authenticate your domain

Inbox providers need to know that email claiming to come from your domain really does. Three DNS records do this:

• SPF lists the servers allowed to send email for your domain.
• DKIM adds a cryptographic signature to each email, which receivers check against a public key in your DNS.
• DMARC tells receivers what to do when SPF or DKIM fail, and where to send reports. Start with p=none to monitor, then move to quarantine once everything passes.

Since 2024, Gmail and Yahoo require all three from anyone sending in bulk. Add your domain in your sending settings and copy the records into your DNS; good email software checks them for you and shows what’s missing.

Send from an address on your own domain ([email protected]), never from a free mailbox like Gmail: those domains publish DMARC policies that make your bulk email fail.

2. Send email people want

Engagement is the strongest signal. When people open, click, reply and move your email out of spam, providers learn it’s wanted. When they delete without opening, or press Report spam, providers learn the opposite.

• Keep complaints below 0.1% of emails delivered. Above 0.3%, Gmail and Yahoo start filtering much more heavily.
• Make unsubscribing obvious. One-click unsubscribe headers let people leave from the inbox itself, and a reader who unsubscribes is far better for you than one who reports spam.
• Send what you promised at signup, at the frequency you promised.
• Segment so that people receive email that is relevant to them.

3. Keep your list clean

Hard bounces (addresses that don’t exist) must never be emailed again. Good software suppresses them automatically. A high bounce rate, above about 2%, signals an old or bought list.

Spam traps are addresses that never signed up for anything, or abandoned addresses that providers have turned into traps. You only hit them by using lists you didn’t collect yourself, or by never cleaning old subscribers out.

Inactive subscribers drag down engagement. Every few months, send a re-engagement email to people who haven’t opened or clicked in four to six months, and stop emailing those who don’t respond.

4. Grow gradually

Inbox providers distrust sudden volume. If you’re moving from another tool or sending from a new domain, start with your most engaged subscribers and increase volume over a few weeks. Don’t send your first campaign from a new domain to an old list of 20,000 people.

5. Write like a person

Content matters less than reputation, but it still matters:

• Avoid all-caps subject lines and piles of exclamation marks.
• Keep a sensible balance of text and images; never send an email that is a single image.
• Use a clear sender name and a reply address that someone reads.
• Include your postal address and an unsubscribe link (good software adds both).

Checklist

• Domain added and SPF, DKIM and DMARC passing
• Sending from an address on your own domain
• Only people who opted in are on your list
• Hard bounces and complaints suppressed automatically
• Complaint rate under 0.1%, bounce rate under 2%
• Re-engagement flow cleaning inactive subscribers
• Volume increased gradually on new domains

If something goes wrong

If opens drop sharply across every email, check your domain records first, then your recent bounce and complaint rates. Look for a recent change: a new list imported, a much bigger send than usual, or a change of sending domain. Pause sending to your least engaged subscribers and send only to people who opened recently until results recover.

Deliverability isn’t a trick or a setting. It’s the sum of sending wanted email to people who asked for it, from a domain that proves who you are.