Deliverability Is a Revenue Problem, Not a Tech Problem

Every few weeks someone messages us asking for help with a domain warm-up, because their open rates dropped from 32% to 19% and they assume the inbox provider is punishing them.

Sometimes that's true. Far more often, they're mailing people who stopped caring two years ago.

The inbox is a mirror

Mailbox providers don't have an opinion about your brand. They measure one thing: whether real people engage with what you send. If you mail 40,000 people and 900 open, the next send lands more often in the promotions tab — not because of a technical setting, but because your list told them what to expect.

That means the fix is usually audience work, not infrastructure work.

The three levers that actually move it

Sunset the dead weight. If someone hasn't opened in twelve months, remove them from regular sends. This feels like shrinking your list. It's the single fastest way to raise engagement rates, because every metric is a ratio and you just improved the denominator.

Send less to people who engage less. A 0–90 day segment can take four sends a week. A 180+ day segment cannot. Sending the same cadence everywhere is how a good list becomes a tired one.

Make the first line of every email do work. Not the subject line alone — the preview text beside it. Together they're the entire decision. Most campaigns we audit waste the preview line on "View in browser."

When it really is technical

Three cases justify the engineering conversation:

• You changed sending domains or added a subdomain and didn't warm it.
• You're sending through a new ESP with no reputation history.
• Authentication (SPF, DKIM, DMARC) is misconfigured or partially aligned.

Those are real. They're also far less common than a list that's been mailed to death.

Where to look first

Pull last quarter's campaigns and sort by segment. Find the cohort with the lowest open rate. Look at how many times you mailed them. That number is usually the whole story.