Bad Sender Reputation? Here’s How To Check Yours and Ultimately Fix It


Bad Sender Reputation? Here’s How To Check Yours and Ultimately Fix It

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Victoria Ang
May 25, 2023

Email is a strong marketing strategy to directly reach your digital audience and keep them informed on product updates, service announcements, special offers, and more.

However, email marketing may prove ineffective if not successfully delivered to inboxes. One key factor that affects email deliverability is your sender reputation. Sender reputation goes by a few common names: Email sender reputation, sender score, domain reputation.

Yet, no matter what you call it, email sender reputation describes how Internet Service Providers (ISPs) like GoogleMicrosoft, and Yahoo judge your outgoing email. More specific inbox providers include Gmail, Outlook, Yahoo, and Hotmail.

How do you determine a good email reputation? That’s where a sender score comes in. Your email reputation sits on a metaphorical scale of 0 to 100. The closer to 100 your sender score is, the better and stronger your email marketing sender reputation is.

This determination is driven by a handful of metrics, but the most important metric is how your digital audience reacts to your email. If your digital audience is interacting with your email, posting positive open and click-through rates, your reputation goes up.

However, common mistakes can hurt your email sender reputation. If you receive too many spam complaints, your reputation goes down. If you send unsolicited emails after buying an email list, your reputation goes down. If you fall into a spam trap or honeypot scam, your reputation goes down.

One of the most common email marketing mistakes is a flagged IP address. This hurts your sender reputation, and many companies don’t realize it happened until it’s too late. So, how does an IP address work with email?

Your email address connects to a specific IP address, which stands for Internet Protocol address. An IP address links all your digital activity to a single “numerical code,” similar to adding a return address to a letter.

You may have multiple email addresses connected to one IP address. You may pay for a private IP address to send only email marketing campaigns from. Either way, this IP address signals to ISPs how good or bad your email sender reputation might be based on the reputation of your IP address.

Now, you have to consider two digital reputations, because they go hand-in-hand.

All email addresses linked to a specific IP address build an IP’s reputation. Together, email addresses and domains belonging to a specific IP address affect an IP’s reputation by judging the quality of outgoing content, contact list, and organic engagement with recipients. (Some companies make the mistake of prioritizing quantity, sending as many emails as they can to as many contacts as they can find — or buy.)

Remember: Your IP reputation and email sender reputation go hand-in-hand. Together, they make or break your ability to reach your audience’s inboxes. For example, the reputation of your IP address can outweigh your sender reputation if a specific email address in your IP sends only unsolicited or unsuccessful email campaigns.

Because these unsuccessful email campaigns are being flagged as spam or unopened and sent to trash, your organic engagement with recipients is poor. This leads to a bad email sender reputation, which in turn affects your IP reputation and other email addresses linked to the IP. It also means your content won’t make it to your email list’s inboxes if you continue to use unrecommended email strategies.

Between sender reputation, sender scores, email deliverability, and IP reputation, it’s a lot to consider in a single marketing strategy. Here are a few basics on how to improve your email sender reputation:

1. Quantity of Spam Flags

To keep a strong sender reputation and high sender score, keep spam complaints low. Otherwise, each time your emails are marked as spam, your sender reputation is damaged.

2. Quality of Email Lists

ISPs are getting smarter about finding poor email senders to protect the privacy of their users. To find these poor senders, ISPs develop email addresses specifically for assessing email campaign senders. As a marketer, if you send an email to any of these email addresses, also known as spam traps or honeypot scams, you can be placed on a public blacklist for email marketing.

To avoid this, don’t buy an email list. ISPs often put these catch-all emails on for-purchase email lists to catch unsolicited senders. Don’t cold-send to email addresses. If you didn’t earn the contact honestly, don’t include them in an email list.

Your email contact list should be organic and full of valid addresses of engaged recipients. These lists are built from lead generation and conversion strategies and result in little to no soft or hard bounces.

  • A soft bounce indicates a temporary email delivery issue. Most email marketing software, like Mirabel’s Marketing Manager, will try to resend the email five times after a soft bounce.
  • A hard bounce indicates a non-existent or invalid email address. (What’s an invalid email address? One that’s deleted, mistyped, or misformatted.) Hard bounces hold stronger weight on your sender score.

A quality list of engaged recipients can also be determined by cleaning and segmenting your email list. If a recipient hasn’t engaged with your last few email campaigns, include them on a “don’t send” list. Don’t send to unverified emails, and segment accordingly to get the best deliverability and open rates.

One surefire way to tidy up an email list is to use an email verification tool like Mirabel Technologies’ Clean Your Lists, which filters out addresses that are invalid and unknown. This increases deliverability and ensures fewer soft and hard bounces.

An email marketing tip on re-engaging contacts is to send out a survey, asking which email campaigns they’re interested in. Do they only want marketing emails? Are they interested in company updates? As you do this, ask for a preferred frequency of when they’d like to receive emails. How’s a monthly newsletter or a weekly product update?

3. Opt-Out Forms

Speaking of valid, engaged email lists, avoid sending emails to unsubscribed contacts. If they opt out and continue to receive emails, they’ll keep trying to opt out and, if to no avail, mark you as spam. This drives your sender score down.

Also, you must include an unsubscribe form on every email. It’s illegal to not include an opt-out form, and if ISPs see an email without one, they’ll flag you, killing your sender reputation.

4. Strong Engagement

Email engagement is determined through open and click-through rates. When recipients open your email, click on links or CTAs, reply and/or forward, they’re engaged and interested. This shows Inbox Providers that you’re welcome. The more often they’re engaged, the higher the sender score.

Infrequent engagement with your email negatively affects your sender score and reputation. Some Inbox Providers even track emails that were ignored, deleted without being opened, or moved to another folder.

5. Sending Frequency

Some email campaigns are flagged as spam because marketers send too many emails, too often. If you send too many emails, you can overwhelm your digital audience. However, if you don’t reach out to your audience enough, you risk losing the interest of subscribers. To avoid both common email mistakes, develop a content schedule that appropriately delivers to your audience.

6. Content Quality

According to SendGrid, “Content includes the words, images, GIFs, templates, links, pre header text, subject lines, and from addresses you use in your emails. All of your email’s content either helps or hurts your reputation. To build a good reputation, you’ll need to send engaging emails that have a professional look and legitimate links.”

Quality content is key when trying to increase your sender score. Stick to your brand’s tone, and use an email template to ensure readability and clean design. Avoid spam words, and test all links before sending your campaign. Size images and GIFs correctly to avoid pixelation on desktop and mobile devices.

7. Authenticate Your Email Domain

Verifying your from address shows your audience that your content is coming from a respectable, legitimate source. Verifying your email domain limits phishing threats and authenticates SPF records, a DKIM signature, and DMARC reporting. Check your email domain with one of these email marketing tools:

According to their website, Barracuda Central maintains a history of IP addresses for known spammers and those with positive email reputations. “This information contributes to the Barracuda Reputation System, which gives the Barracuda Spam & Virus Firewall the ability to block or allow a message based on the sender’s IP address.”

In addition to IP reputation, Barracuda Central maintains URL reputations, which allow the tool to quickly block an email based on a poor URL contained in the content. By combining the IP and URL reputation data, Barracuda Central determines whether or not an email is spam. Once identified, the tool implements countermeasures to mitigate these digital threats and reinforce its claimed 95 percent spam accuracy rate.

Talos Intelligence determines where your sender score lies on a qualitative range from “Poor” to “Neutral” to “Good”:

  • A good sender score means jeopardizing behavior to your sender score occurs infrequently.
  • A neutral score indicates room for email deliverability improvement, because they’re being filtered away from your recipients at a noticeable rate.
  • A poor score means that your emails have substantial difficulty appropriately reaching those in your email contact.

Talos Intelligence even tracks global malware outbreaks and shows users legitimate emails versus spam rates per country, IP address, and more.

After creating an email deliverability test account, this robust email marketing tool creates a personalized email address to send test campaigns to. After sending a test campaign to this address, SendForensics estimates your sender score and analyzes your sender reputation, giving you an immediate snapshot of your IP reputation so you can troubleshoot any issues beyond the emails themselves.

This free resource gives insight into how a widely common email domain assesses your emails addressed to their users. After claiming ownership of your domain, Google analyzes your sender reputation based on four qualitative categories: Bad, Low, Medium, and High.

In addition, Google’s Postmaster Tools investigate how many times your email has been reported for spam amongst several other features affecting email deliverability.

Like Google’s Gmail, Microsoft Outlook is one of the largest Inbox Providers in the world. With its own set of Postmaster-like tools, Microsoft offers Smart Network Data Services (SNDS). This email deliverability tool allows anyone with an IP address to take up the fight against spam, viruses, and malware, protecting not only their email, but the Internet as a larger communication tool.

After confirming your IP address, SNDS gives you data about the traffic seen originating from your IPs. It can also give you email data, including activity period, traffic data, SMTP verb and message recipient counts, and sample commands.

In regards to email deliverability, SNDS shows users filter results. Spam verdicts resulting in Green mean less than 10 percent spam, Yellow is between 10 and 90 percent spam, and Red is over 90 percent spam. It also displays junk mail data, including complaint reportstrap hitssample messagesvirus-infected emailsmalware hosting, and open proxy status.


With a dozen marketing strategies to improve your sender reputation and email deliverability, it’s time to up that sender score.

For more information about how to improve your sender score, download A Beginner’s Guide to Email Marketing by Mirabel’s Marketing Manager:


Watch an overview to learn how B2B marketing automation by Mirabel Technologies can help you increase traffic, optimize your funnel, drive more leads, improve conversions, and boost ROI — at a price you can afford!

A Beginner’s Guide to Email Marketing

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