Vatsal Shah You can write the best cold email in the world—and still end up in spam.
The problem is neither your email copy nor your offer: it’s your email reputation that’s working against you!
So, if your open rates are dropping or replies are slowing down, and you can’t pinpoint the problem, you’ve come to the right place!
After launching hundreds of successful cold outreach campaigns, I’ve learned exactly what it takes to improve and maintain a high email reputation for both new and inactive accounts.
In this blog, I’ll show you how to improve your email reputation fast, avoid spam filters, and launch campaigns that actually get seen.
Read on and say goodbye to the spam folder!
Improve Email Reputation– TOC
What is Email Sender Reputation?
Email sender reputation is a score that reflects how trustworthy you are as a sender in the eyes of email service providers.
It’s based on your sending behavior — how often you send emails, how recipients interact with them, and whether your emails trigger spam complaints or bounces.
What is the role of email sender reputation?
A strong sender reputation means you:
- Emails consistently reach the primary inbox
- Get better open and reply rates
- Domain and IP remain trusted over time
A poor reputation can lead to:
- Low open rates due to spam folder placement
- Reduced engagement or outright delivery blocks
- Long-term damage to your email domain
If you’re running cold outreach campaigns, your sender reputation directly affects your ROI.
How is email reputation calculated?
It’s calculated based on how you send emails, like:
- How often do prospects open or reply to your emails
- Whether your emails bounce
- If recipients are marking your emails as spam
Here’s a rough idea of what your score means:
- 90–100: Your emails are inbox and ESP-friendly
- 70–89: Good, but you can strengthen it to improve inbox placement
- 50–69: Some of your emails might hit the spam folder
- Below 50: Big red flag, urgent action needed
How to Check Email Reputation for Free
The best way to check your sender reputation is to use the native postmaster tools for your ESP.
For example, popular ESPs offer free postmasters you can use to verify your sender reputation.
How do ESPs Determine Sender Reputation?
To build or improve your email reputation, you first need to understand how your ESP (email service provider) decides whether you’re a trusted sender or someone who looks like a spammer.
Here are the 6 key factors that ESPs evaluate to determine your sender reputation:
Explore them in detail!
1. Spam Complaint Rate
If too many recipients mark your emails as spam, your ESP will take that as a signal that your emails aren’t welcome and start sending them directly to the spam folder.
To protect your sender reputation, you should maintain a spam complaint rate of less than 0.1%. That means fewer than 1 complaint per 1,000 emails sent.
Anything above that, and your ESP has a strong reason to lower your trust score.
2. Bounce Rate
When you send emails to invalid or outdated addresses, they bounce. Occasional bounces are fine. But if your bounce rate consistently goes above 2%, that’s a red flag.
Most ESPs tolerate bounce rates up to 1%–2%. Ideally, you should stay below 1% to avoid hurting your reputation.
A high bounce rate usually means your contact list isn’t clean, and ESPs interpret that as poor sending hygiene.
3. Spammy Content
Using words like “free,” “discount,” “limited time,” or “guaranteed” doesn’t automatically land you in spam, but it increases the risk, especially if your audience doesn’t engage with your emails.
Moreover, modern ESPs don’t just look at keywords. They evaluate whether your content looks promotional, manipulative, or clickbait in combination with poor engagement (low opens or clicks).
Hence, if your content looks spammy and users ignore it, your reputation will drop!
4. IP Reputation
If an ESP detects too many bounced or spammy emails from a single IP address, it may label the entire IP address as a source of spam.
So, while your email reputation largely depends on your sending patterns, your IP address could also be the reason your email reputation is down.
5. Sending Volume
Sending thousands of emails in one go, especially from a new or inactive account, is one of the fastest ways to kill your sender reputation.
So, if you send 200 emails one day and 5,000 the next, the sudden spike will raise flags.
The best approach is to warm up your inbox gradually and follow a consistent sending pattern.
This shows ESPs that you’re a legitimate sender, not a spam bot!
6. Email Authentication
Even if everything else is right, clean list, safe content, and low spam rate, if your domain isn’t authenticated, your emails will still land in spam.
Most ESPs require the proper setup of:
- SPF (Sender Policy Framework)
- DKIM (DomainKeys Identified Mail)
- DMARC (Domain-based Message Authentication, Reporting, and Conformance)
Without authentication, your emails look unverified and suspicious.
Read on to find out how you can meet ESP guidelines and improve your sender reputation!
10 Best Practices to Improve Email Reputation
Now that we’ve covered what email reputation is and how ESPs calculate it, let’s look at 10 proven practices to improve your sender reputation and keep your campaigns out of the spam folder.
- Switch to a Dedicated IP Address
- Authenticate Your Email Domain
- Use an Email Warmup Service
- Include an Unsubscribe Link
- Personalize Your Outreach Emails
- Regularly Clean Your Email List
- Rotate Sending Accounts
- Monitor Email Deliverability Metrics
- Don’t Track Open Rates
- Conduct an Email Deliverability Audit
Let’s explore them!
1. Switch to a Dedicated IP Address
If you’re using a shared IP address, your reputation is affected by everyone else sending from the same IP, even if you’re following best practices.
A dedicated IP gives you full control over your sending behavior and keeps your reputation isolated from others.
Pro Tip: If you’re sending over 150,000 emails per month, you should definitely switch to a dedicated IP.
2. Authenticate Your Email Domain
The past year has been challenging for email deliverability: several users reported a decline in both deliverability and open rates.
Plus, the inbox placement rate in 2025 is down even for popular ESPs like Amazon SES, MailGun, and MailChimp.
And it’s no surprise that these trends have occurred at the same time as ESPs rolled out new authentication requirements.
As a part of the new guidelines, you must set up three email authentication records:
- SPF: To prevent unauthorized use of your domain.
- DKIM: To ensure that your email contents are not tampered with.
- DMARC: To help you decide what to do with emails that don’t meet SPF and/or DKIM verifications.
These records prevent email spoofing and protect users from phishing attacks.
This leaves you with two options:
❌ Skip authentication – land in spam – reduce sender reputation ✅Authenticate your email domain – land in inboxes – improve email reputation.
So, when you think about it, you really only have one option: set up your authentication records and ensure they work properly!
Check out this detailed guide to easily set up your SPF, DKIM, and DMARC records.
3. Use an Email Warmup Service
New and inactive email accounts need time to build trust with ESPs. That’s what email warmup does — by gradually increasing volume and creating positive engagement signals.
But manually warming up several accounts can be difficult.
That’s where automated email warmup tools come in!
This helps your ESP view you as a consistent, trusted sender, without manual effort.
The best email warm-up services help by:
- Sending low-volume emails to trusted inboxes
- Opening, replying to, and removing emails from spam
- Mimicking real human conversations over time
- Ramping up your send volume slowly
This way, you can improve your email reputation without doing any heavy lifting!
4. Include an Unsubscribe Link
One of the quickest ways to damage your email reputation is by making it difficult for recipients to opt out of your emails.
If users can’t easily unsubscribe, they’re more likely to mark your emails as spam, which directly hurts your sender score.
When including an unsubscribe link, ensure that it is clearly visible and in a standard location, like the email footer.
Plus, including an unsubscribe link will also help you comply with privacy laws like CAN-SPAM and GDPR.
5. Personalize Your Outreach Emails
While generic emails get marked as spam, personalized emails get you higher open rates, replies, and engagement.
But as inboxes become more and more crowded, using your recipient’s first name in the first line is not enough anymore…
Luckily, there are excellent cold email service providers that can help you personalize cold emails at scale, through features like merge tags, variable tags, spintax, and AI sequences.
These cold email platforms will help you ensure that your recipients will think that your email was written for them, and no one else!
6. Regularly Clean Your Email List
The #1 reason for high bounce rates is using email lists with invalid or unverified email addresses.
And, as we’ve seen, if your bounce rate crosses 0.3%, your email reputation could be in big trouble!
There are three ways you can overcome this problem:
- Buy email lists only from highly reputable B2B data providers
- Use an email verification tool to clean your email list before sending cold emails
- Create a policy of cleaning your email database every 2-3 months
7. Rotate Sending Accounts
Building a sender reputation is one thing, but maintaining it even while sending high-volume cold email campaigns is quite another!
The most effective way to protect your email reputation is to utilize sender rotation.
This will ensure that even if one of your email accounts faces a dip in its sender reputation, your overall domain health remains unaffected.
And the best way to ensure that you don’t have to manually switch senders is to use a cold email software that offers automated sender rotation.
Pro Tip: Choose a cold email tool that automatically optimizes your emails’ delivery path by matching each recipient’s ESP, for example, Outlook-to-Outlook or Gmail-to-Gmail sends. This will improve your inbox placement rate.
8. Monitor Email Deliverability Metrics
As we’ve seen above, ESPs use specific metrics to measure your overall email reputation.
And a drop-off in just one critical area, like the bounce or spam rate, can reduce your email reputation.
So, you should always take a proactive approach and regularly monitor key email deliverability metrics, such as:
- Spam Rate
- Number of bounces
- Reply Rate
- Click-throughs
- Unsubscribe Rate
These metrics will give you an overview of whether your cold email campaign is working or if you need to tweak your strategy to maintain your email reputation.
9. Don’t Track Open Rates
While tracking open rates is both standard, it might actually hurt your email reputation!
Here’s why:
To track open rates, you need to include tracking pixels: when a recipient opens your email, their email client downloads the pixelated image.
However, some ESPs (like Google and Outlook) consider using tracking pixels as suspicious behavior.
In turn, this automatically increases the risk of your emails landing in the spam folder, just because you’re tracking open rates!
So, play it safe: avoid tracking open rates.
Plus, you can measure user engagement just as effectively by tracking reply and click-through rates.
However, if at all you want to track your open rates, you should use a custom tracking domain.
This will isolate your email sending activity from shared tracking domains and help you win the ESP’s trust!
10. Conduct an Email Deliverability Audit
The best way to check the overall status of your domain is to conduct an email deliverability audit.
A deliverability audit is a thorough and systematic check of the factors that affect your sender reputation and inbox placement.
It will give you an overall snapshot of your domain health and allow you to spot trends before they become major problems.
Check out this guide to learn everything you need to know about email deliverability audits!
Say Goodbye to the Spam Folder with High Email Reputation
Through this blog, I’ve walked you through the A-Z of how to build and improve your email reputation.
Let me quickly summarize the key takeaways you should keep in mind:
- Follow ESP guidelines on authentication and sending limits
- Respect your recipients’ privacy through double opt-in
- Regularly track deliverability metrics that impact email reputation
- Use a combination of the best email warmup and cold email tools
I’ll leave you with one last tip:
After you’ve done the hard work and improved your email reputation, use an email deliverability checklist.
Following the checklist will help you safeguard your domain health, whether you’re sending small batches of emails or executing high-volume cold email campaigns!
Improve Email Reputation: FAQs
1. What is a good deliverability rate for email?
A good deliverability rate for email is generally considered to be over 95%. However, for B2B emails, the standard email deliverability rate is 98%. Plus, your email deliverability rate will also depend on:
- The ESP you use
- The industry you work in
- The region in which you operate
2. Does email warmup improve email reputation?
Yes, email warmup definitely improves email reputation. It’s a proven method of gradually building trust with an ESP. Email warmup involves maintaining conversational threads with highly reputable email accounts and steadily increasing the sending volume. When repeated over 2-4 weeks, it tells the ESP that you’re a trusted email sender.
3. How does IP warmup improve email deliverability?
IP warmup improves email deliverability by slowly increasing email volume from a new IP to build trust with ESPs. It gradually introduces your IP to the ESP as a legitimate email sender and conveys that you’re sending relevant emails to its users.
4. How to fix email deliverability for Microsoft Outlook?
In my experience, you should use a combination of tactics to fix email deliverability for Microsoft Outlook:
- Set up your SPF, DKIM, and DMARC authentication records
- Use a cold email service that offers ESP Matching for optimized email delivery paths
- Regularly update and clean your email lists to minimize the bounce rate
- Avoid using promotional language or words that might trigger Outlook spam filters
- Use Outlook’s Postmaster to monitor deliverability metrics and fix issues proactively
