Domain reputation is the score Gmail, Microsoft and the other big mailbox providers keep on your sending domain. It is the single biggest reason two brands can send the same wholesale pitch to the same buyer and one lands in the inbox while the other goes to spam. Nobody publishes the score, it moves with every send, and it is surprisingly easy to damage in a week and slow to repair. This guide covers what domain reputation is, what actually moves it, how to check it with the free tools that exist, and what to do when it has gone wrong.
If you are still setting up a sending domain, start with SPF, DKIM and DMARC first. Reputation is built on top of authentication, not instead of it.
Domain reputation versus IP reputation
Mailbox providers track two things about you: the IP address the mail came from and the domain in your From address and DKIM signature. Years ago IP reputation mattered most. Today, because almost every small sender is on shared Google or Microsoft infrastructure, the IP is shared with thousands of other senders and tells the receiver little. The domain is what identifies you, so the domain is what carries the history.
That is good news and bad news. Good, because a small brand on Google Workspace inherits Google's excellent IP standing. Bad, because every mistake you make is pinned to a domain you own and cannot swap out without starting again.
What actually moves the score
Providers do not publish their formulas, but the signals are consistent across all of them:
- Bounces. Sending to addresses that do not exist is the fastest way down. A high hard-bounce rate tells the provider you are sending to a list you did not earn. This is why you verify every address before you send; the numbers in our buyer email verification data show how many wholesale buyer addresses fail that test.
- Spam complaints. A buyer clicking "report spam" counts far more than one ignoring you. A handful of complaints on a small volume is a serious signal.
- Spam trap hits. Addresses maintained purely to catch senders using scraped or stale lists. One hit can land you on a blacklist.
- Volume patterns. A domain that sent 5 emails a day for a month and then 400 on Tuesday looks like a compromised account. Steady, gradually rising volume looks like a real business.
- Engagement. Opens, replies, messages moved out of spam, and messages the recipient replies to all count in your favor. Deleted-without-reading and archived-instantly count against you.
- Authentication and consistency. Passing SPF, DKIM and DMARC, keeping the same From name and address, and sending from the same infrastructure all build trust.
- Content. Less important than people think, but link-heavy templates, tracking pixels on every message and spammy phrasing still get flagged.
Notice that most of the list is about who you send to and how much, not what you write. A brilliant email to a dead list still wrecks your domain.
How to check domain reputation
There is no single number, but you can triangulate it from a few sources, all free.
Google Postmaster Tools
Google's own dashboard for senders. You verify ownership of your domain and it shows you a domain reputation rating on a simple scale (bad, low, medium, high), your spam rate as Gmail measures it, authentication pass rates and any delivery errors. It only shows data once you are sending enough volume to be statistically meaningful, so a brand-new domain will show nothing for a while. Set it up on day one anyway so the history is there when you need it.
Microsoft SNDS
Microsoft's equivalent, Smart Network Data Services, reports on the IP addresses sending to Outlook and Hotmail. It is IP-based, so on shared Google or Microsoft infrastructure it is less useful, but it is worth registering if many of your buyers are on Microsoft 365, which most mid-sized retailers and distributors are.
Blacklist lookups
A blacklist check site queries dozens of public blocklists for your domain and sending IP in one go. A listing is a hard fact, not a score, and usually points directly to the cause.
Your own numbers
The most honest measure is what your outreach data says. Track bounce rate, reply rate and the share of sends that get any engagement at all, week by week. If replies from a steady, verified list suddenly fall off a cliff and bounces have not changed, reputation is the usual suspect. Tracking cold outreach results covers which numbers to watch.
Inbox placement tests
Seed-list services send your message to a set of test mailboxes across providers and report where it landed. Useful for a snapshot, but do not over-read a single test; run one before and after any change instead.
How to fix a damaged domain
When the checks come back bad, the temptation is to change the subject line and try again. Resist it. Follow this order.
- Stop sending from the domain. Every additional send while the reputation is low makes it worse. Pause all campaigns.
- Find the cause. Look at bounces first, complaints second, volume spikes third. If you are on a blacklist, the listing entry usually names the reason.
- Fix the list. Run every remaining address through a verification tool and remove anything that is invalid, catch-all with low confidence, or role-based. If the list was bought or scraped, throw it away.
- Fix the setup. Re-check SPF, DKIM and DMARC, remove tracking pixels if you were using them, and make sure your unsubscribe or opt-out line is clear and works.
- Cut volume and re-warm. Restart at a handful of emails a day to your most engaged contacts, and increase slowly over several weeks, the same way you would warm up a new domain. Replies during this phase are what rebuild the score.
- Request delisting where relevant. Most blocklists have a self-service removal form once the cause is fixed.
Repair typically takes several weeks. If the domain was hammered badly, hit multiple traps, or you simply cannot wait, retiring it and starting a fresh, properly warmed domain is often faster than rehabilitation. That is one more reason never to do outreach from your main brand domain.
Protect the domain that matters
Your primary domain carries your store, your order emails, your Amazon brand registry correspondence and your customer service. Keep cold outreach off it entirely. Use one or more separate sending domains, each with its own mailboxes, and treat them as replaceable. If a sending domain gets burned, you lose a few weeks and a domain registration, not your business email.
Within a sending domain, keep each mailbox at a modest daily volume. Spreading 60 emails a day across three mailboxes on two domains looks like three people doing their jobs; 60 from one address looks like a campaign.
A worked example
Say a kitchenware brand builds a list of 400 independent cookware shops from a directory, does not verify it, and sends 200 emails on day one from a new domain. Forty bounce. Two shop owners hit "report spam." By day three, Postmaster Tools shows the domain at low reputation and replies have stopped.
The fix: pause everything, verify the remaining 360 addresses (say 250 survive), set up Postmaster Tools properly, and restart at 10 emails a day to the shops most likely to reply, adding a few more each week. Reply rate recovers over about a month. The brand keeps that domain for outreach and never sends from its store domain again. Slower, but the pipeline actually works.
Most of the damage in that example came from one avoidable thing: sending to unverified addresses. WholesalePilot is built around not doing that — it finds the distributors and retail buyers for your product, verifies every email before anything goes out, and sends the outreach in your name at a volume that protects the domain rather than burning it.
Domain reputation is a savings account. Every verified, wanted email is a deposit; every bounce is a withdrawal with a fee.
Paste your product link and see the verified buyers before you send a single email — the preview is free.