Written by
Tim Collins
Published on
18 August 2026
A client rang me a while back, genuinely baffled. They had spent real money on a campaign. Good copy, a designer on the template, an offer that had worked for them before. The send report said every message went out. The open rate came back at four per cent.
Nothing was wrong with the campaign. The problem happened before a single recipient had the chance to look at it.
This is the first of four articles about domain reputation, which is the quiet mechanism that decides whether your email gets seen at all. It is the thing most senders have never heard of and every mailbox provider cares about more than anything else. Over the series we will cover what it is, who scores it, what it costs when it slips, and what we do about it. Start here.
Your email does not go where you think it goes
When you hit send, the message does not travel to your recipient. It travels to whoever runs their mailbox. For most Australian lists that is Google or Microsoft, with a share going to Yahoo, Apple, and the local providers like Telstra and iiNet.
That provider now has a decision to make, and roughly a fraction of a second to make it. Inbox, promotions tab, junk, or refuse the message outright.
They are not reading your email to decide. They do not have time and, frankly, they do not care what it says. They are asking one question about the domain it came from: based on what happened recently, do people want mail from this sender?
Domain reputation is the answer to that question. It is the running record of how recipients have responded to your mail, and it is the single biggest factor in whether your campaign arrives.
It is not a credit rating, though people reach for that comparison
The credit rating analogy gets used a lot and it is close enough to be useful, but it misleads in one important way.
A credit rating is built on history. Years of it. Something you did five years ago still shows up. Domain reputation is almost the opposite. It is built on the last few weeks, and older behaviour fades out of the picture surprisingly fast.
That cuts both ways, which is the part worth sitting with. A domain that has been sending badly can recover in a matter of weeks if the sending changes. A domain with a spotless record can lose its standing just as quickly by going quiet or sending one bad campaign. There is no score you earn once and keep.
What actually moves it
Nobody sits in an office rating your domain. Reputation accumulates automatically, from what recipients do and from what your sending setup looks like from the outside.
The things that build it are the things a wanted sender produces naturally. People open the mail. They reply to it, forward it, click through. They pull it out of junk when it lands there, or add you to their contacts. Your volume is steady week to week rather than lurching. Your authentication is clean, so the provider can prove the mail genuinely came from you. Your unsubscribe works and you honour it promptly.
The things that damage it are just as ordinary. People mark you as spam. They delete without opening, again and again. You send to addresses that no longer exist and the mail bounces, which we covered in more detail in our article on email validation. You hit a spam trap, one of the dead addresses providers maintain specifically to catch senders working from stale lists. You go quiet for two months and then send four thousand emails in an afternoon. Or you send from a brand new domain with no history at all, which to a provider looks indistinguishable from a spammer who registered a domain that morning.
Notice what is not on either list
Read back through and you will see something missing. The quality of your writing. Your design. Your offer. How well the campaign is targeted.
Those things matter enormously, but only once the email is in front of a human being. They have almost no bearing on whether it gets that far.
This is the part that catches people out, and it is why my client's four per cent open rate had nothing to do with the money they spent on copy. You can write the best email of your career and it will sit in a junk folder if your domain's recent record says people do not want your mail. The provider filtered it before the copy ever came into play.
It is worth saying the reverse too, because it is the more useful half. Fix the reputation and an ordinary campaign starts performing like a good one, because it is finally being measured on whether people liked it rather than on whether they saw it.
Your whole domain, not just your campaigns
One more thing before we move on, because it surprises people.
Reputation attaches to your domain, not to a particular type of mail. There is no separate lane for marketing and another for the important stuff. If your domain's standing slips because of a poorly targeted campaign, the quote you send a prospective client the following week travels on the same reputation. So does your invoice. So does your reply to a customer who emailed you first.
That is the real risk, and it is why we treat deliverability as infrastructure rather than as a marketing setting. A domain in good standing is a business asset. One that has been allowed to slide is a liability that shows up in places you are not watching.
Next in the series
Part two looks at who is actually doing the scoring. There are two distinct groups, they work differently, and one of them recently changed how it reports back to senders in a way that caught a lot of people out.
If you would rather not wait, domain warming is how we keep our clients' reputations in good standing, and it is built into every FlipSend account rather than sold as an extra.