If the email never reaches the inbox, the subject line is irrelevant. Deliverability is whether Gmail, Outlook and the rest trust you enough to put the message in front of a person.
Open rate is a different problem. From lines, subjects and snippets are covered in the three things you can control. This page is the technical and list-hygiene side we fix on email retainers when a client says “nobody is opening anything” and the real issue is that nobody is seeing it.
What a good open rate is actually telling you
If you are under 15%, something is broken. Often it is not the copy. It is spam placement, a cold list, or authentication that was never set up.
Around 25% is ordinary for a lot of B2B lists. 30% and up is a sensible target once the mail is landing and the from line is familiar. Those numbers still mix two things: did it arrive, and did they care. Split them in your head or you will rewrite subjects for a year while sitting in spam.
Prove you are you: SPF, DKIM and DMARC
Mailbox providers want proof the domain in the from address is allowed to send this message. Think of it as showing ID at the airport, for email.
- SPF is the guest list. It says which servers may send mail for your domain.
- DKIM is the wax seal. It signs the message so it cannot be quietly altered in transit.
- DMARC is the policy. It tells receiving servers what to do when SPF or DKIM fail, and it sends you reports so you can see who is sending as you.
If those records are missing, wrong, or pointing at a tool you stopped using, a slice of mail never arrives. Tools like HelloInbox will show you the current state. Your DNS host and your email platform (Kit, Customer.io, Google Workspace) both have to agree. This is the unglamorous work. It is also the work that moves the number.
The list is usually the quiet problem
A list of people who asked to hear from you, recently, from a form on your site, is easy to deliver. A list you bought, scraped, or imported from a 2019 conference export is not. Providers watch complaints, bounces and whether people ever engage. They do not care that you “only send value”.
What we tell clients to do, in order:
- Remove hard bounces as they happen, not in a quarterly tidy-up.
- Stop mailing addresses that have not opened or clicked in a long time. For a weekly newsletter that is often three to six months, not three years.
- Use double opt-in when the list is growing from ads or a lead magnet. One extra click saves you a year of spam-folder pain.
- Segment. A client, a prospect and a newsletter reader should not get the same send if you can help it.
Bought lists and scraped LinkedIn exports are how domains get a reputation they cannot shake. We do not use them.
What still sends good mail to spam
Authentication and a clean list are the foundation. You can still trip the filters with the message itself.
- Subject lines in all caps, fake urgency, and “FREE!!!” belong in 2004.
- Image-only emails with almost no text look like ads, because they are.
- Sending from a brand-new domain at high volume is a fast way to get blocked. Warm the domain up.
- Links through two layers of tracking redirect, plus a mismatch between the visible URL and the destination, look like phishing.
Write like a person. Send from a domain you own. Link to pages you control. That covers more “spam trigger” lists than another article about magic words.
A 30-minute deliverability check
- Look up SPF, DKIM and DMARC for the sending domain. Fix whatever is missing before you touch the copy.
- Send a test to a Gmail, an Outlook/Microsoft 365, and a personal address you do not open every day. See where it lands.
- Export the last 90 days of bounces and complaints from your ESP. Clean them.
- Count how much of the list has not engaged in six months. Pause those people.
- Then, and only then, work on the from line, subject and snippet.
Email that people want to read still has to arrive. Get it into the inbox first. Make it worth opening second.
