Skip to content
Supercharge Your Pipeline
Close up image of two hands typing in a laptop while checking emails

Mastering Email Deliverability Part 2: Optimizing Email Sender Reputation and Building Trust with ISPs

Unleash the full potential of Klaviyo with a comprehensive audit!

May 7, 2024

By Alen Čapelja

Whether we like it or not, reputations have a way of getting ahead of us and making first impressions on our behalf. In this second installment of our email deliverability series, we’re focusing on how to optimize email sender reputation and build trust with internet service providers (ISPs). 

What Is Email Sender Reputation?

Sender reputation reflects the level of trust that ISPs have placed in your brand’s emails. This rating is tied to the IP address your marketing emails are sent from and any associated domains, making it essential to monitor and prioritize good standing. 

Factors of Influence: What Determines Email Sender Reputation

From the volume of emails sent to the number of spam complaints, your email sender reputation is influenced by a range of factors inbox providers review to determine whether your emails are safe (and relevant) to deliver. They include but are not limited to: 

  • Sender history 
  • Unsubscribe rate 
  • Engagement rates
  • Bounce rates 
  • Spam complaints
  • Spam traps 
  • Blocklists 

Review email marketing benchmarks to define baseline performance levels by industry and gain perspective on the strengths and weaknesses of your sender reputation. 

How to Check Your Email Sender Reputation

Email service providers (ESPs) typically evaluate senders every 30 days. However, similar to a credit score, email sender reputation will vary with each source because the data, algorithms, and methodologies for assessment are not universal.

Free resources such as Sender Score can provide an overview of your current sender reputation, but they have limited capacity for additional insights (e.g., blocklist lookups).  

HubSpot also provides several tools and features to help users check the health of their emails. One key feature is the email health dashboard, which provides insights into key metrics such as open rates, click-through rates, and bounce rates. HubSpot offers email testing tools that allow users to preview how their emails will appear on different devices and email clients, ensuring a consistent and professional appearance. The platform also provides recommendations for improving email deliverability, such as avoiding spammy language and ensuring that emails are properly formatted. 

For more detailed analysis, some ESPs offer proprietary resources to qualified, high-volume senders to monitor their reputation and email deliverability, such as Postmaster Tools by Gmail. 

Groundwork for Building Trust with ISPs

These steps will be essential to complete in advance of any new email campaigns to give your sender reputation credibility. 

Establish a Dedicated Sending Domain (DSD)

Before rushing into any changes, create a strong foundation for email deliverability. Configure authentication and trust protocols to allow ISPs to verify your identity as a sender more easily. 

This will give you greater legitimacy and control over your email sender reputation. When sending emails from new or previously inactive domains, do not overlook a DSD. For more information, see “Mastering Email Deliverability Part 1.” 

Gradually Roll Out Changes

ISPs rely on sender history to manage expectations. This can be a significant obstacle for new or inactive domains. Start with limited email volumes and gradually increase over time, building trust with inbox providers through responsible sending practices. 

Avoid Spam Filters and Blocklisting 

Erratic or sudden changes in sending behavior can appear suspicious and cause your emails to be sent to spam folders. It can even lead to blocklisting by ISPs. Warming up your domain helps signal that your email-sending practices are legitimate. 

Implementing a Domain Warming Plan

Once you’ve created a new DSD, strategically increase the volume of emails for a gradual buildup that minimizes the risk of negative engagement.

Develop a Warming Schedule 

Plan to increase email send volume with a limited number of recipients over a period of four weeks or more, incrementally increasing the number of recipients. 

Segment Engagement Groups 

Utilize segmentation to group recipients based on engagement and relevant customer demographics. Start with the most engaged users, gradually including less active ones, as your warming plan aligns with significant campaign efforts.

Increase Implementation Volume

Start with no more than 10,000 email recipients per send. Throughout the warming process, monitor deliverability metrics so you can optimize your sending schedule, engagement, and content strategy. 

Include your most engaged users in each send as you progressively ramp up to a daily cadence. If necessary, use smart send to divide these users into smaller groups that receive the send at a delay. For user segments you want to re-engage, include them in sends twice per week and make adjustments based on engagement and deliverability metrics.  

Improving Sender Reputation Over Time

A good sender reputation takes time to establish and maintain. It will be a long-term effort to improve deliverability, enhance engagement, and actively mitigate risk.

Keep Your List Up to Date

Email addresses can become defunct for any number of reasons, from job changes to name changes. Regularly clean your email list of invalid addresses and disengaged subscribers to limit the number of undeliverable and unread emails. 

Review Bounce Code 

Although a clean email list will help reduce your bounce rates and improve your sender reputation, it’s still important to review bounce codes. Hard bounces are simple enough to resolve by updating your suppression list, but soft bounces indicate more nuanced deliverability concerns. Make sure to proactively review and address bounce codes to maintain a positive sender reputation.

Segment Email Sends

You can’t be everything to everyone. Segmentation can be especially impactful when combined with the warming process to refine your content strategy and improve email performance. 

Prioritize Content Engagement

To boost open and click-through rates, include your most engaged subscribers in broad email sends. This allows you to achieve higher levels of interaction with emails and will positively influence your domain's sender reputation. For more targeted campaigns, explore opportunities to improve email formatting, design, and copy to support more engagement. 

Monitor Performance and Adjust as Needed 

In order to optimize email sender reputation, closely monitor how your emails perform so you can identify trends and make necessary adjustments in real time. This will reduce the risk of significant deliverability concerns and contribute to a healthy reputation.

Reporting to Optimize Email Sender Reputation

Analysis of the domain warming process will offer actionable insights to improve deliverability, email performance, and sender reputation. A reporting plan will give structure to ongoing optimization with measurable outcomes to inform your email marketing strategy. 

Gather Data from Your Content Management System

Whether it lives in your CMS or any platform that integrates with your email marketing, assemble data for all negative and positive engagements that impact deliverability and sender reputation. Reports should include open rates, click rates, spam complaints, unsubscribe rates, bounce rates, and any additional performance metrics that may be a priority for your campaign. 

Identify Actionable Takeaways

To identify strategic priorities, analyze and compare key performance indicators (KPIs) with industry benchmarks and your baseline performance metrics prior to domain warming. This will guide where you need to take action for improved deliverability and where your efforts are already on target. 

Maintain Follow-Ups

For long-term success, continue to review deliverability and sender reputation, making necessary adjustments as your relationship with email subscribers evolves.

InLine CTA for blog content, Email Deliverability Series Part 3: Demystifying Email Authentication Protocols + Compliance Requirements


Rebuild Your Sender Reputation with Expert Support

Without a foundation of trust and responsible sending practices, inbox providers will be inclined to view your emails as spam, limiting the potential of your marketing campaigns. Email sender reputation is paramount for successful deliverability. 

If the process of building trust and optimizing sender reputation with a domain warming plan is beyond your team’s capacity, reach out to our deliverability experts. We can take the necessary steps to check your sender reputation and develop and implement an optimization plan aligned with your email marketing goals. 

Ready to rebuild your sender reputation? Get in touch! 


Unleash your full email marketing revenue potential with a comprehensive audit!

Klaviyo Optimization and Deliverability Audit

Check It Out
Topics: Marketing Strategy, Email Marketing, E-Commerce Marketing