Checklist for Maintaining a Clean Sender Reputation

Silvio Bonomi
1 day ago
16 min read

Updated: 59 minutes ago

Your sender reputation determines if your emails reach inboxes or get flagged as spam. A poor reputation can hurt email deliverability, increase bounce rates, and damage your brand's credibility. Fixing it takes weeks or months, so proactive management is crucial.

Here’s how you can maintain a clean sender reputation:

Authenticate Emails: Use SPF, DKIM, and DMARC protocols to prove you're a legitimate sender and avoid spam filters.
Warm Up Dedicated IPs: Gradually increase email volume to build trust with providers.
Clean Email Lists: Remove invalid or inactive addresses and avoid buying lists.
Personalize Content: Tailor emails to your audience for higher engagement.
Monitor Reputation: Use tools like Sender Score and blacklist alerts to track and fix issues.

Quick Tip: Even one spam complaint per 1,000 emails can hurt your reputation. Regularly clean your lists, monitor metrics, and follow best practices to keep your emails in inboxes.

Expert Tips on Advanced Email Deliverability & Building a Strong Sender Reputation

Email Authentication Setup

Email authentication acts as your email's ID card, proving to providers that you're a legitimate sender. This process helps your messages avoid spam filters and land in the right inboxes. Without it, even the most carefully planned campaigns might get flagged or ignored.

Set Up SPF, DKIM, and DMARC Protocols

To safeguard your emails, you need to implement three key protocols: SPF, DKIM, and DMARC. Each plays a unique role:

SPF ensures only authorized IP addresses can send emails on your behalf.
DKIM adds a digital signature to verify your email's integrity.
DMARC combines SPF and DKIM to enforce domain alignment and provides instructions for handling unauthenticated emails.

Valimail: "DMARC, DKIM, and SPF are three must-have email authentication methods every business should use. Collectively, they prevent phishers from harming your customers (and your brand's reputation)."

Here’s how they work together: DMARC relies on SPF and DKIM to strengthen domain protection. While it requires at least one of these protocols to pass, using both is recommended. DMARC also checks domain alignment and tells mail servers what to do with emails that fail authentication - mark them as spam, deliver them, or reject them entirely.

Domain alignment can get tricky. For example, if a user requests a password reset from Mailtrap, they might receive an email from no-reply@mailtrap.io, but the return-path address could look like "bounces+8208408-cfe8-user=domain.com@em9554.mailtrap.io". With strict SPF alignment, DMARC would fail because the domains don’t match. However, with relaxed settings, the alignment test would pass.

To make these protocols effective, ensure your sending IP is configured properly by using a dedicated IP address.

Configure Dedicated IP Addresses

A dedicated IP address gives you full control over your sender reputation and email deliverability. Unlike shared IPs - where other senders' bad practices can hurt your reputation - a dedicated IP ensures that your outcomes are based solely on your own sending habits.

To get started, you'll need to "warm up" your dedicated IP. Start by sending 50–100 emails daily to engaged recipients, slowly increasing volume over 2–4 weeks.

Platform	Dedicated IP Price	Requirements	Notes
HubSpot	$300/month	Professional/Enterprise plans	Ideal for high-volume enterprise senders
Mailchimp	$29.95/month	Add-on available	Affordable option for smaller teams
Marketo	Custom pricing	100,000+ emails/month	Tailored for enterprise solutions

For instance, one SaaS client ran into trouble with spam filters after an aggressive Black Friday campaign. By adopting a 4-week warmup strategy, they boosted their deliverability rate from 45% to 87%, generating an extra 50 qualified leads per month - all without altering their messaging or targeting. Additionally, keeping bounce rates below 2% is linked to a 23% higher chance of emails landing in inboxes across major providers.

Once your IP is set up, the next step is to maintain your DNS records.

Update DNS Records Regularly

Think of your DNS records as the address book for email authentication. Even a small typo in these records can cause major delivery problems. Regular updates and monitoring are essential to avoid issues.

Accurate DNS records validate your email protocols and support your sender reputation. This becomes especially crucial during system changes, like migrating to a new server or updating your email platform. Tasks may include updating cryptographic keys, revising DNS zone files, or adjusting security policies. It’s also important to validate all DNS, A, MX, SPF, and DKIM records for accuracy.

Don’t overlook reverse DNS setup. Create a PTR record that matches your mail server's IP address to ensure proper configuration. Regularly review DNS logs and conduct security audits to identify vulnerabilities. One common mistake is failing to update the serial number after making changes on the primary server, which can prevent secondary servers from recognizing updates and lead to propagation failures.

For businesses like Artemis Leads, which depend on consistent email outreach to engage decision-makers, keeping DNS records accurate is critical. Regular maintenance ensures that your authentication protocols stay effective, protecting both your deliverability and your brand's reputation.

Email List Management

Keeping your email list clean and engaged is essential for better deliverability, higher open rates, and fewer spam complaints. On the flip side, poor list management can harm your sender reputation significantly.

Just one spam complaint per 1,000 emails can impact your reputation as a sender, making it crucial to focus on building and maintaining high-quality email lists.

Build Email Lists Organically

Avoid buying email lists at all costs. Purchased lists often contain outdated or irrelevant data and can trigger spam traps, damaging your credibility.

Instead, focus on growing your list through organic strategies that attract people who are genuinely interested in your content. In fact, 53% of small business owners across the U.S., U.K., Canada, and Australia rely on email marketing as their primary tool for customer acquisition and retention.

"What sets email apart is ownership. When platforms change their rules overnight, your email list remains untouched. It's the most reliable direct channel marketers have in an increasingly unpredictable digital marketing space."– Evaldas Mockus, VP of Growth at Omnisend

Here are some effective ways to grow your email list organically:

Offer valuable lead magnets: Provide white papers, ebooks, exclusive discounts, or free trials in exchange for email addresses. Make sure your offer is clear and appealing.
Use exit-intent pop-ups wisely: These pop-ups, triggered when a visitor is about to leave your site, can be effective if done right. While the average conversion rate is around 3%, well-designed pop-ups can hit 10%.
Leverage social media: With 91% of mobile users active on social platforms, promote your lead magnets there to encourage signups.
Incorporate signup opportunities into customer touchpoints: Add email capture forms to your checkout process, embed signup buttons in your emails, or enable text-to-join options for mobile users.

For B2B businesses like Artemis Leads, focusing on organic list building is even more critical. High-quality contacts who genuinely want to hear from you are more likely to engage, improving your overall email performance and ensuring your messages reach the right decision-makers.

Use Double Opt-In for New Subscribers

Double opt-in requires subscribers to confirm their email address before being added to your list. While it adds an extra step, it’s one of the best ways to ensure list quality and protect your sender reputation.

Nearly 40% of senders already use double opt-in to verify new subscribers. This method ensures the email address is valid, the subscriber is genuinely interested, and bots are kept out of your forms.

"I would recommend that every sender use a double opt-in all the time. Not only does it ensure you only acquire subscribers who are more likely to engage, but it also helps prevent bots from abusing signup forms, which is a significant email security risk."– Nick Schafer, Sr. Manager of Deliverability & Compliance, Sinch Mailgun

Double opt-in also provides documented proof of consent, which is crucial for GDPR compliance and other data protection laws. Plus, confirmation emails often see high open rates, making them a great starting point for your onboarding process.

Feature	Single Opt-in	Double Opt-in
Signup Process	One-step	Two-step (confirmation email)
List Quality	Lower, may include invalid addresses	Higher, verified email addresses
Engagement	Lower	Higher
Deliverability	Lower	Higher
List Growth	Faster	Slower
Legal Compliance	May require embedded consent language in forms	Provides clear documentation of subscriber consent

How to implement double opt-in effectively:

Enable double opt-in in your email platform settings.
Personalize the confirmation email to reflect your brand’s tone.
Clearly explain the two-step process on your signup form so subscribers know what to expect.
If someone doesn’t confirm within 24 hours, send a polite reminder email to nudge them.

Once your list is verified through double opt-in, focus on maintaining its quality through regular cleaning.

Clean and Validate Email Lists

Email lists naturally degrade over time. In fact, email databases decay by about 22% annually. People change jobs, abandon old accounts, or simply lose interest in your content.

To keep your list in top shape, follow these steps:

Set a regular cleaning schedule: Identify inactive subscribers - those who haven’t opened an email in 90 days or clicked a link in six months - and decide whether to try re-engaging them or remove them.
Focus on meaningful actions: Prioritize metrics like clicks, downloads, or purchases over vanity metrics such as open rates.
Use email validation tools: Tools like Bouncer, ZeroBounce, and NeverBounce can automatically identify invalid or risky emails. For example, Clearout found that 18% of a client’s B2B email list was invalid or risky. After cleaning, inbox placement improved by 42%, and open rates jumped from 12% to 26%.

"Regularly verifying your email list is like tidying up your workspace, it keeps your campaigns efficient and your audience engaged. By ensuring every address is valid, you reduce bounce rates and build trust with your recipients, leading to more successful Outreach."– Bill Stathopoulos, CEO @SalesCaptain

Make unsubscribing easy by keeping the unsubscribe link visible and simple to use. It’s better to let uninterested users leave than risk them marking your emails as spam, which can hurt your sender reputation.

Run re-engagement campaigns to revive inactive subscribers. Offer compelling content or exclusive deals to win them back. If they remain unresponsive after a few attempts, it’s time to remove them from your list.

Email Content Best Practices

Creating high-quality email content is key to building and maintaining a strong sender reputation. With nearly half of all email traffic classified as spam, engaging and relevant content not only boosts deliverability but also protects your reputation as a sender. Below, we explore three key strategies - personalization, formatting integrity, and clear unsubscribe options - that can help you improve your email campaigns.

Personalize Email Content

Personalization is all about crafting messages that resonate with your audience’s specific interests, behaviors, and preferences. It’s no secret that personalized emails perform better: subject lines tailored to the recipient can increase open rates by 20%, while click rates see a 139% boost compared to generic emails. In fact, 71% of consumers report that personalized experiences influence their decision to engage with emails.

Here are some ways to personalize effectively:

Segment your audience: Group your contacts by factors like industry, job role, company size, or location. This allows you to send targeted messages that feel relevant to each group.
Leverage dynamic content: Use recipient data to customize fields within your emails, such as personalized product recommendations or localized offers.
Send triggered emails: Automate follow-ups based on user actions. For example, a B2B company like Artemis Leads might send a follow-up email after someone downloads a white paper or attends a webinar.
Do your homework: Research your contacts thoroughly to address their unique needs and challenges. Craft your emails to spark meaningful conversations instead of pushing for immediate sales.

"In my opinion, the use of a CRM is a very important factor. With it, you will be able to create the best possible segmentations, in addition to contacting customers in the best channels for each of them and offering what they want at the right time."– Paulo Moreira, Customer Success Manager, OmniK

"You're a guest in your subscriber's inboxes, so respect what they have told you. Whether that's their overall preferences and topics, or if they say they want their emails in Dark Mode, or they sign up for your newsletter and nothing else, you have to honor that."– Carin Slater, Manager of Lifecycle Email Marketing at Litmus

Avoid Spam Triggers and Poor Formatting

Keeping your emails out of spam folders is essential for maintaining a good sender reputation. This means avoiding common spam triggers and ensuring your emails are well-formatted.

What to watch out for:

Spam trigger words: Words like "free", "urgent", "limited time", or "guaranteed" can set off spam filters. While not outright banned, overusing them can push your email into the spam folder.
Balance text and images: Aim for a 60% text and 40% image ratio to avoid looking like spam. Emails that are too image-heavy may trigger filters.
Use clean HTML code: Poorly formatted HTML or broken links can signal spam. Always test your emails across different platforms to ensure they display properly.
Incorporate multimedia wisely: Adding a video can boost open rates by 19% and click-through rates by 65%. Just ensure videos are embedded or linked properly, rather than sent as large attachments.
Focus on readability: Use clear subject lines that reflect your content, avoid excessive capitalization or exclamation points, and organize text with headings, short paragraphs, and white space. Including your company’s physical address and contact details in the footer adds transparency and builds trust.

Include Clear Unsubscribe Options

Providing an easy way for recipients to opt out of your emails isn’t just polite - it’s legally required and crucial for maintaining your sender reputation. Statistics show that 53% of people aged 18 to 24 and 64% of those aged 55 to 64 unsubscribe from marketing emails they no longer want to receive.

Clear unsubscribe options also reduce the likelihood of your emails being marked as spam, which directly impacts your reputation. With the acceptable spam rate threshold at just 0.08%, even a small number of complaints can hurt your deliverability.

Since February 2024, platforms like Google and Yahoo have enforced stricter standards, requiring bulk senders (5,000+ emails daily) to include a one-click unsubscribe option using a List-Unsubscribe header.

"Allowing your recipients to easily unsubscribe is not only good manners, it's also a good deliverability practice to follow. It will help reduce your overall spam rates, improve your reputation, and ensure that you're sending emails to an active audience going forwards, which will strengthen your inbox rate. Deliverability is all about aligning yourself with your recipients' expectations, and allowing them to unsubscribe is just one simple way to do just that."– Alexandre Zibrik, Compliance and Deliverability Engineer, Sinch Mailjet

Best practices for unsubscribe options:

Make it easy to find: Place the unsubscribe link at the bottom of your email with clear language like "Unsubscribe" or "Stop Receiving Emails".
Simplify the process: Use a single-click unsubscribe option. Avoid requiring recipients to log in or navigate multiple steps.
Offer preferences: Let subscribers choose the type or frequency of emails they receive instead of opting out entirely.
Act quickly: Remove unsubscribed users from your list immediately to avoid frustration and potential legal issues. Violating the CAN-SPAM Act can result in fines of up to $53,088 per email.
Confirm the unsubscribe: Send a clear confirmation message to reassure users that their request has been processed.

"The unsubscribe button lets users declutter their inboxes by easily opting out of emails that no longer interest them. This not only improves the user's experience, but also encourages marketers to send more relevant and targeted content."– Maddy Watson, Social Media Student Worker, West Virginia University

Sender Reputation Monitoring

Your sender reputation is like an email credit score - it determines whether your emails land in the inbox or get banished to the spam folder. With only 58% of users checking their spam folders daily compared to 95% who check their main inbox, keeping a strong reputation is essential if you want your messages to reach your audience effectively. While strong authentication and clean email lists lay the groundwork, consistent monitoring ensures you catch and fix issues before they affect your deliverability.

Track Sender Score and Key Metrics

Think of sender reputation monitoring as an early warning system. Keeping tabs on key metrics allows you to catch potential problems before they snowball into major issues. The key areas to monitor include your sender score, bounce rates, complaint rates, and engagement levels.

The Sender Score, a free tool from Validity, assigns your IP address a rating between 0 and 100, giving you a snapshot of how mailbox providers perceive your email practices. Other tools like Google Postmaster Tools, Microsoft SNDS, Barracuda Central, MXToolbox, and MailTester provide additional insights across various platforms.

Tool	Key Features
Sender Score	Rates IP reputation on a 0-100 scale
Google Postmaster Tools	Provides Gmail-specific data on deliverability
Microsoft SNDS	Offers reputation data for Outlook/Hotmail
Barracuda Central	Categorizes reputation as good or poor
MXToolbox	Sends alerts for reputation changes
MailTester	Analyzes messages and server configurations

By combining data from several sources, you can gain a more complete picture of your sender reputation. Make it a habit to monitor these metrics weekly and look for trends, such as spikes in bounce rates or dips in engagement, so you can act quickly if something seems off.

Set Up Blacklist Monitoring Alerts

Getting blacklisted can wreck your email deliverability in an instant, so proactive monitoring is critical. Blacklists are databases of IP addresses and domains flagged for sending spam. These lists are maintained by various organizations, and major providers like Google and Microsoft also maintain their own private lists alongside public ones.

To stay ahead, set up blacklist monitoring alerts. Tools like MXToolbox and Online Domain Tools can check your IP against multiple DNS-based blackhole lists (DNSBLs) and real-time blackhole lists (RBLs). These services typically scan your IP every 8 to 24 hours and notify you via email, SMS, or webhook if you’ve been listed.

If you rely on an email service provider or an SMTP relay service, they often handle blacklist monitoring for shared IPs. But for high-volume senders or those using their own SMTP servers, dedicated monitoring is essential.

If you do find yourself on a blacklist, speed is key. Each blacklist has its own removal process, so you’ll need to investigate and follow their specific instructions. Some removals happen automatically after a waiting period, while others require manual requests and evidence that the issue has been resolved. After resolving the issue, review your engagement metrics and adjust your email strategy to prevent future problems.

Analyze Engagement and Adjust Strategies

Engagement metrics are a direct reflection of your sender reputation. High engagement tells mailbox providers that recipients value your emails, which strengthens your reputation. On the other hand, low engagement can hurt your deliverability over time.

Keep an eye on metrics like open rates, click-through rates, and conversion rates to gauge how recipients are interacting with your emails. If your deliverability rate dips below 95%, it’s time to dig deeper. Regular analysis can help you identify trends and make adjustments before they escalate. For example, declining open rates or rising spam complaints might signal the need to refine your audience segmentation, improve subject lines, or tweak your sending frequency.

CampSaver, an outdoor gear retailer, is a great example of how proactive engagement monitoring can pay off. After noticing some of their emails were landing in spam folders, they partnered with Validity to address the issue. As a result, they improved their sender reputation and had greater confidence in their holiday campaign performance.

For B2B companies like Artemis Leads, engagement analysis plays an even bigger role. Business decision-makers expect highly relevant, personalized content. By monitoring how prospects interact with your outreach emails, you can fine-tune your messaging and boost meeting booking rates. Whether it’s testing different send times, revising your content strategy, or cleaning up inactive subscribers, acting on your data can help you maintain a strong sender reputation and keep your emails where they belong - in the inbox.

Conclusion: Maintain Your Sender Reputation Long-Term

Keeping a strong sender reputation isn’t a one-time task - it’s an ongoing effort that directly impacts your bottom line. Considering email marketing delivers an average return of $42 for every $1 spent, ensuring your emails consistently land in inboxes is crucial. By focusing on technical verification, managing your email lists carefully, crafting engaging content, and monitoring performance regularly, you can create a system that supports long-term success.

High spam complaints highlight why these steps matter. If your deliverability rate falls below 95%, it’s a clear sign of reputation issues. Addressing these problems consistently is essential to maintaining your ability to connect with your audience.

For B2B companies like Artemis Leads, which combine personalized email campaigns with LinkedIn outreach, a strong sender reputation is the backbone of their strategy. When both channels work together to target 100% of their ideal customer profile, email deliverability becomes a key factor in booking meetings and generating leads. A solid reputation ensures your carefully crafted messages reach decision-makers instead of getting lost in spam folders.

"Improving your sender reputation from 60 to 85 can increase your qualified leads by 40% without sending a single additional email."
Lance D'Souza, Chief Marketing Officer at SmartReach.io

This approach doesn’t just protect your deliverability - it also enhances the quality of your leads. Long-term success means treating your sender reputation as an ongoing relationship with Internet Service Providers (ISPs), rather than just a technical challenge. Regularly cleaning your lists and quickly addressing issues can improve open rates and prevent setbacks.

"Deliverability is a measure of the health of your email marketing program, so it's important to do regular check-ups on your domain, IP, and authentication in particular to make sure you're up-to-date, just like how we all go to the doctor each year."
Carin Slater, Manager of Lifecycle Email Marketing at Litmus

FAQs

How do SPF, DKIM, and DMARC work together to protect email deliverability?

SPF, DKIM, and DMARC: The Email Security Trio

SPF, DKIM, and DMARC work together to ensure your emails land where they’re supposed to - while keeping spoofing and fraud at bay.

SPF (Sender Policy Framework): This protocol checks if the email is sent from a server that’s authorized to send on behalf of your domain. It’s like a bouncer verifying IDs at the door.
DKIM (DomainKeys Identified Mail): Think of this as a tamper-proof seal. It adds a digital signature to your email, proving it hasn’t been altered during its journey.
DMARC (Domain-based Message Authentication, Reporting, and Conformance): DMARC connects the dots between SPF and DKIM. It tells email providers how to handle messages that fail these checks and provides detailed reports on authentication activity.

When combined, these three protocols create a powerful shield. They help build trust with email providers, reduce the chances of your messages being marked as spam, and protect your domain’s reputation. Setting them up is a must if you want your emails to consistently hit the inbox.

What should I do if my email IP address is blacklisted?

If your email IP address ends up on a blacklist, the first step is to figure out which blacklist flagged it. Most blacklists have a process for removal, so head to their website or reach out to their support team to request delisting.

After that, take a close look at your email sending practices. Make sure you're following best practices, like setting up proper email authentication protocols () and keeping a clean, permission-based contact list. These steps can help prevent future issues with blacklisting.

If your IP is dynamic, restarting your modem or network equipment might temporarily fix the problem. However, if the issue keeps cropping up, it’s a good idea to consult an expert who can help identify and resolve any deeper issues in your email setup.

Double opt-in is a method where subscribers confirm their email address by clicking a verification link, usually sent to their inbox. This extra step ensures that only people who genuinely want to receive your emails make it onto your list. As a result, it minimizes spam complaints and improves the chances that your emails actually reach inboxes.

This process is also important for meeting GDPR requirements. By securing clear and explicit consent from users, double opt-in helps your business stay on the right side of data protection laws and reduces the risk of legal issues tied to unsolicited emails. Beyond compliance, it helps you build a more engaged email audience and keeps your sender reputation intact.

Checklist for Maintaining a Clean Sender Reputation

Expert Tips on Advanced Email Deliverability & Building a Strong Sender Reputation