Domain Reputation: How to Check and Fix for Cold Email

What is Domain Reputation?

Domain reputation is a score email providers assign to your domain based on your sending history. It determines whether your emails reach the inbox or spam.

Think of it like a credit score. When you have good reputation, your emails get the benefit of the doubt and land in the inbox. With bad reputation, email providers assume you’re spam and route you to the junk folder. And if you have no reputation at all, like a new domain with zero history, providers view you with suspicion.

Every single email you send affects your reputation. When recipients open your emails, reply to them, or click the “not spam” button, you’re building positive reputation. When they hit “report spam” or your emails bounce, you’re destroying it. The math is simple, but the consequences are serious.

Why Domain Reputation Matters for Cold Email

Cold email is inherently riskier than sending newsletters to people who signed up for your content. You’re contacting strangers who didn’t ask to hear from you. The numbers tell the story clearly.

When you send marketing emails to subscribers who opted in, you might see spam complaint rates around 0.01 percent. That’s barely a blip. But when you’re doing cold outreach to people who’ve never heard of you, spam complaints jump to anywhere from 0.5 to 2 percent. That’s fifty to two hundred times higher.

This higher complaint rate means domain reputation becomes absolutely critical for cold email success. You don’t have the cushion of extremely low complaint rates that newsletter senders enjoy. One bad campaign with a poorly targeted list can tank your deliverability for weeks.

How to Check Domain Reputation

Google Postmaster Tools - Your Most Important Resource

Google Postmaster Tools shows your reputation specifically with Gmail, which handles more than half of all B2B email inboxes. If you only check one tool, make it this one.

To get started, head to postmaster.google.com and add your domain. You’ll need to verify ownership by adding a DNS record. Once you’re in, you’ll see dashboards showing your domain reputation level, spam rate, authentication status, and encryption compliance.

Google rates your reputation on a simple scale: High, Medium, Low, or Bad. High reputation means you’re an excellent sender with normal inbox delivery. Medium indicates some issues and possible filtering. Low reputation means significant problems and likely spam folder placement. Bad is exactly what it sounds like—you’re either blocked entirely or going straight to spam.

Your target should always be High reputation with a spam rate under 0.1 percent. If you see anything less, it’s time to investigate.

Microsoft SNDS for Outlook and Microsoft 365

Microsoft’s Smart Network Data Services shows your reputation with Outlook, Hotmail, and Microsoft 365 accounts. Given how many businesses use Microsoft email, this matters.

Visit sendersupport.olc.protection.outlook.com/snds to sign up. You’ll need to verify ownership of your sending IP addresses. Once verified, you can see your IP reputation, spam filtering data, and complaint rates.

Microsoft uses a color-coded system. Green means you’re good to go with low complaint rates. Yellow indicates caution. Red means serious problems. Keep your status green and your complaint rate as low as possible.

Talos Intelligence for General Reputation

Cisco’s Talos Intelligence provides a broader view of your domain and IP reputation across the internet, not just specific email providers.

Go to talosintelligence.com/reputation_center and enter your domain or IP address. You’ll get a reputation score ranging from Good to Blacklisted. Good means normal sending. Neutral indicates no history or mixed signals. Poor means you have deliverability issues. Bad or Blacklisted means many providers are blocking you.

Blacklist Checkers - Your Early Warning System

Blacklists are databases of domains and IPs that have been reported for spam or abuse. If you land on a major blacklist, your deliverability plummets overnight.

Use tools like MXToolbox Blacklist Check, Spamhaus, and Barracuda Central to scan dozens of blacklists at once. Your target is simple: zero blacklist listings, ever.

Creating a Checking Routine

Don’t wait for problems to emerge. Set up a weekly routine where you check Google Postmaster for your reputation and spam rate, run a blacklist check, and review your bounce rate in whatever tool you use for sending.

Then do a monthly deep dive across all the tools. Look at trends over time. Are things improving or declining? Catching a downward trend early gives you time to fix issues before they become disasters.

What Affects Domain Reputation

Reputation Killers - The Negative Factors

Spam complaints are the most severe reputation killer. When someone clicks “report spam,” email providers take notice. Anything over 0.1 percent complaint rate is a serious problem.

Bounce rates destroy reputation almost as fast. If more than 5 percent of your emails bounce, you’re sending to bad addresses, and providers assume you’re a spammer who bought a list. High bounce rates suggest you don’t know your recipients and don’t care about sending quality.

Spam traps are email addresses set up specifically to catch spammers. They’re never used by real people, so if you’re sending to them, you either scraped addresses from websites or bought a terrible list. Any spam trap hits are a problem.

Low engagement rates signal that people don’t want your emails. If fewer than 10 percent of recipients open your messages, providers start to question whether you should be in the inbox at all.

Volume spikes look suspicious. If you normally send 100 emails per day and suddenly send 2,000, providers assume you’ve been hacked or you’re launching a spam campaign. Never increase volume more than 20 percent in a single day.

Reputation Builders - The Positive Factors

Opens help, but not as much as you might think. When recipients open your emails, it signals mild interest. Aim for at least 40 percent open rates.

Replies are gold. A reply is the strongest signal that your email was wanted and valuable. Target at least 5 percent reply rates, and your reputation will stay strong.

“Not spam” actions are incredibly powerful. When someone finds your email in their spam folder and clicks “not spam” to move it to their inbox, that’s a massive positive signal. Even a few of these can offset dozens of neutral sends.

Consistent volume matters. Sending roughly the same number of emails every day signals that you’re a legitimate business with predictable communication patterns.

Low complaint and bounce rates build reputation over time. Keep complaints under 0.05 percent and bounces under 2 percent, and you’re demonstrating sender quality.

The Engagement Equation

Your reputation essentially comes down to a ratio: positive signals divided by negative signals. Positive signals include opens, replies, clicks, and “not spam” actions. Negative signals include spam complaints, bounces, and complete lack of engagement.

Here’s the harsh reality: you need significantly more positive signals than negative ones. One spam complaint might require 100 positive engagements to offset. The math is brutal, which is why list quality and targeting matter so much.

Building Domain Reputation

Starting Fresh with New Domains

New domains have no reputation. They’re neutral, but email providers view them with suspicion. Too many spammers use fresh domains to avoid their bad reputation.

In your first week or two, focus entirely on setup and warmup. Configure your authentication records properly—SPF, DKIM, and DMARC. Start sending warmup emails through services that exchange messages between real accounts to build positive history. Don’t send any cold email yet. Your only goal is establishing that your domain exists and sends wanted mail.

During weeks three and four, continue warmup while adding small amounts of real email. Send maybe 10 to 20 emails per day to people you have existing relationships with—past clients, colleagues, warm leads. These should be emails that get high engagement. You’re building on the positive foundation you established.

After week five, you can begin careful cold outreach. Start with just 20 to 30 emails per day. Scale slowly, maybe 10 percent per week. Monitor your reputation constantly. If you see any dips, slow down or pause until you identify the cause.

Recovering Existing Domains with Issues

If your domain already has reputation problems, recovery follows a different path. First, stop the bleeding. Reduce your sending volume or pause entirely. Remove any problematic lists from your sending queue. Fix technical issues like broken authentication.

Second, diagnose what went wrong. Check Google Postmaster for specifics about your reputation issues. Review your recent sends for patterns. Was it a bad list? Did you send too much volume too fast? Did your email content trigger filters?

Third, fix the root cause. If you had a bad list, clean your remaining lists aggressively. If your content was spammy, rewrite it. If your sending patterns were suspicious, adjust them. If you’re on blacklists, follow the delisting procedures.

Fourth, rebuild slowly. Start warmup again as if you were a new domain. Send small volumes only to your most engaged recipients. Monitor metrics like a hawk. Scale up very gradually.

This recovery timeline typically takes two to eight weeks depending on how badly your reputation was damaged.

Reputation Recovery Scenarios

Scenario One: The Minor Dip

You notice your open rates dropped 10 to 20 percent over the past week. When you check Google Postmaster, you’ve slipped from High to Medium or Low reputation. Some of your emails are landing in spam folders.

This usually happens after one bad send—maybe you used a poorly targeted list or your email content was too salesy. The fix is relatively straightforward: reduce your volume by half, clean your upcoming sends carefully, focus on quality over quantity, and monitor closely for one to two weeks. Most domains recover from minor dips in two to three weeks.

Scenario Two: The Major Drop

Your open rates have crashed below 10 percent. Most of your emails are going to spam. Your bounce rate is climbing. Google Postmaster shows Low or Bad reputation.

This signals a significant issue. Maybe you hit spam traps from a purchased list, or you scaled volume too aggressively, or you had multiple bad sends in a row. Recovery requires more drastic action: pause all cold email immediately, run warmup only for two weeks, audit all your processes and lists, then restart with verified lists at very low volume. Recovery from a major drop takes four to six weeks.

Scenario Three: Blacklisted

Your emails are bouncing outright or being blocked. When you check blacklists, you’re listed on major databases. Your reputation is marked as Bad across the board.

Blacklisting happens from severe issues—hitting spam traps, receiving many complaints, or clear abuse patterns. Stop all sending immediately. Identify which blacklists you’re on and why. Follow each blacklist’s delisting process, which often requires proving you’ve fixed the underlying issues. Be prepared for recovery to take four to eight weeks, or consider whether starting with a fresh domain makes more sense.

Protecting Domain Reputation

The Secondary Domain Strategy

Never, ever send cold email from your primary business domain. If something goes wrong with your cold outreach, you don’t want your main domain’s reputation destroyed along with it.

Set up secondary domains specifically for cold email. If your business is yourcompany.com, use domains like getyourcompany.com or tryyourcompany.com for cold outreach. Keep your primary domain pristine by only sending warm emails from it—replies to customers, follow-ups with people who contacted you, emails to existing relationships.

The benefit of this approach is huge. If your cold email domain gets damaged, you can pause sends from it, start recovery, or even abandon it for a new domain. Meanwhile, your primary domain remains safe and functional.

List Quality Controls

Every email address you send to should pass quality checks. Verify addresses using services like ZeroBounce or NeverBounce to catch invalid, temporary, and spam trap addresses before you send. Use recent data, because email lists decay about 30 percent per year as people change jobs and abandon addresses. Target your ideal customer profile carefully so you’re sending to people who might actually care. And make sure you have either opt-in consent or legitimate business interest in contacting each person.

Volume Management

Sending volume needs careful management. Keep it to a maximum of 50 to 100 emails per mailbox per day. Never increase volume more than 20 percent in a single day. Spread your sends throughout the day rather than blasting everything at once. And if you need higher volume, use multiple mailboxes rather than overloading a single one.

Content Best Practices

Your email content affects deliverability too. Plain text performs better than HTML for cold email. Keep links to a maximum of one or two per email. Avoid images entirely in cold outreach. Personalize content so it’s relevant to each recipient. Make your sender identity crystal clear so people know who’s emailing them.

Monitoring System

Set up automated alerts for key metrics. Get notified if your bounce rate exceeds 3 percent. Alert yourself if open rates drop more than 20 percent. Flag any spam complaints immediately. Monitor reputation status changes from Google Postmaster. Catching problems early makes them much easier to fix.

Key Takeaways

Domain reputation is the single most important factor in cold email deliverability. Check your reputation weekly using Google Postmaster Tools so you spot issues before they become disasters. Keep your bounce rate under control, because high bounce rates above 5 percent destroy reputation faster than almost anything else. Remember that reputation takes weeks to build but only days to ruin, so protect it carefully. If you’re using a new domain, build reputation gradually before scaling your volume. And if you need to recover from reputation damage, plan for at least two to eight weeks of careful, conservative sending focused on high engagement.

Your domain reputation literally controls whether your cold email campaigns succeed or fail. Protect it like your business depends on it, because it absolutely does.

Need a Reputation Audit?

We’ve helped dozens of companies recover domains from the brink of being unsalvageable. We’ve also built bulletproof sending infrastructure from scratch that maintains excellent reputation even at high volume.

If you’re worried about your current reputation, experiencing deliverability problems, or want your cold email setup done right from the start, book a call with our team. We’ll audit your situation and show you exactly how to fix it or build it properly.