You can write the best email of your life and it earns nothing if it lands in spam. Deliverability is the part of email marketing store owners ignore until revenue drops, and by then the damage has built up over months. This is how inbox placement works and what to do about it.
Two things decide where your email lands: whether mailbox providers can prove the message came from you, and whether the people who get your mail act like they want it. The first is a one-time technical setup. The second is an ongoing habit. You need both.
Key takeaways
- Two things set placement: proving the mail is yours, and recipients acting like they want it.
- Publish one SPF record, turn on DKIM, and start DMARC at p=none before tightening.
- Send marketing from a subdomain so a bad campaign cannot hurt your order confirmations.
- Keep spam complaints under one per thousand and sunset subscribers who stop engaging.
Authentication: prove the mail is yours
Gmail and Yahoo now require authentication for anyone sending to their users at volume. This is not optional. Three records do the work, and they live in your domain's DNS.
SPF
SPF is a list of the servers allowed to send email for your domain. When a message arrives, the receiving server checks whether it came from an approved sender. If your email platform is not on that list, you fail the check.
Your email service provider gives you the value to publish. Publish one SPF record per domain. Two SPF records on the same domain break each other, and that is a common mistake when a store adds a second sending tool.
DKIM
DKIM adds a cryptographic signature to every message. The receiver checks the signature against a public key in your DNS. If it matches, the message was not altered in transit and it genuinely came from your domain. Turn on DKIM in your email platform and publish the keys it gives you. This is the single strongest signal that you are who you claim to be.
DMARC
DMARC ties SPF and DKIM together and tells receivers what to do when a message fails both. It also sends you reports on who is sending mail using your domain, which surfaces spoofing.
Start with a monitoring policy so you can watch the reports without blocking anything:
v=DMARC1; p=none; rua=mailto:[email protected]Once the reports confirm your legitimate mail is passing, tighten the policy to p=quarantine and later p=reject. Moving straight to reject before you have read the reports can block your own order confirmations.
Use a subdomain for marketing
Send marketing from a subdomain like news.yourdomain.com and keep transactional mail such as receipts and password resets on the main domain or a separate one. If a promotional campaign hurts your reputation, your order confirmations still reach the inbox. This one decision protects the mail your business cannot afford to lose.
Reputation: act like a sender people want
Authentication proves identity. It does not prove people want your mail. Mailbox providers watch how recipients behave, and that behavior sets your reputation.
The signals that help you: opens, replies, clicks, and people moving your mail out of spam and into the inbox. The signals that hurt you: spam complaints, deletes without opening, and hits on spam-trap addresses. Above roughly one complaint per thousand messages, providers start routing you to spam. Keep complaints under that line.
List hygiene: the habit that decides everything
Most deliverability problems trace back to sending to people who do not engage. Clean the list and the numbers recover.
- Use double opt-in or a strong single opt-in. Confirming the address at signup keeps typos and fake entries off the list. Never buy a list. Purchased lists are full of spam traps that wreck a sending reputation in one send.
- Sunset unengaged subscribers. If someone has not opened or clicked in 90 to 120 days, move them to a win-back sequence. If they stay silent, stop mailing them. A list of 20,000 people who open is worth more than 100,000 who do not.
- Suppress hard bounces immediately. A hard bounce means the address does not exist. Keep mailing it and you look like a sender who does not maintain a list.
- Watch role addresses. Addresses like info@ and sales@ tend not to engage and raise complaint risk.
Warm up before you scale
If you switch platforms or start a new sending domain, do not send to your whole list on day one. Providers distrust a brand-new sender that suddenly pushes 50,000 messages. Start with your most engaged subscribers, the people who opened in the last 30 days, and increase volume over two to three weeks. Early engagement from your best contacts builds the reputation that carries the rest of the list.
Content signals that trip filters
Authentication and reputation do most of the work, but content still matters at the margin. Avoid these:
- A message that is one large image with almost no text. Filters cannot read it and treat it as a hiding tactic.
- Link shorteners and mismatched domains. Link to your own domain.
- Spam-trigger phrasing in the subject line, all caps, and rows of exclamation marks.
- A missing plain-text version. Every email should ship with both HTML and plain text.
A diagnostic order that saves time
When placement drops, work in this order:
1. Confirm SPF, DKIM, and DMARC pass for every recipient. Send a test to a checking service and read the results.
2. Check your complaint rate and bounce rate in your platform. If complaints are high, you are mailing people who do not want it.
3. Look at engagement by segment. If your unengaged segment is dragging the whole list down, cut it.
4. After those pass, look at content and design.
Takeaway
Set SPF, DKIM, and DMARC once and use a subdomain for marketing. Then protect reputation every week by mailing engaged people, sunsetting the silent ones, and keeping complaints under one per thousand. Deliverability is not a trick. It is proving your identity and behaving like a sender people asked to hear from.