There’s a lot of misunderstanding around domain reputation when it comes to email sending and email deliverability. Domain reputation is a thing, and it does relate to email and email deliverability, and it is important. For example, it is absolutely the case that if example.com starts spamming, inbox providers are going to start putting email from example.com into the junk folder, or maybe even block it altogether. But still, domain reputation is not what a lot of people think that it is.
Because a lot of what domain reputation really is, i.e. what it’s largely based on, when it comes to email deliverability, is your email reputation. Does the email coming from your domain have a good reputation? Are you following all of the best email practices, and do the recipients of your email want it and interact with it or, at very least, not report it as spam?
These have been the base requirements for getting your email delivered ever since the very beginning of email marketing. You need to send only permission-based email, you need to have your authentication set up, you need to include an unsubscribe link and to process unsubscribes in a timely manner, ditto for bounces. If you don’t, you are going to end up with more and more of your email being moved to the spam folder.
And, similarly, if the recipients of your email are reporting your email as spam, or even just if enough of them are deleting your email without opening it, the inbox providers may start putting more of your email in the junk folder.
This is all basic email deliverability and reputation 101. It’s email reputation. But hey, your email comes from your domain. So again, yes, domain reputation is important, but in the email deliverability world it’s based on the quality of the email that you send, and on your practices related to that email. It’s like the reputation of a house: if a house has a reputation as a crackhouse, it’s because of the activities going on within that house, and what’s coming out of the house – the house’s reputation as a crackhouse has nothing to do with whether the house is a Tudor-style or ranch house, nor that it is at 123 Main Street (although that address can become associated as being the address of a notorious crackhouse, just like a domain can become associated as being notorious for being a source of spam).
Bottom line: when it comes to email deliverability, domain reputation is largely predicated on and related to email reputation, and email reputation is built by following all best sending practices. If you send bad email from example.com, example.com is going to get a bad reputation in terms of email.
Or, put another way, that crackhouse has a reputation as a crackhouse because of what’s going on inside. To rehabilitate the house’s reputation, the occupants need to stop the those activities, not paint the house or put new address numbers on the front.