Top 16 Email Marketing Metrics for Affiliate Marketers to Track in 2025
Emails are always sent out with some purpose in mind, whether it’s to sell a product, teach something, or introduce a new product feature. Affiliate email marketers come up with these reasons and draft their emails to fit them perfectly, but their job doesn’t just stop the moment they press “send.”
Writing the email is only the first part of the equation – but analyzing the results of that email is where the real fun begins!
Email analytics are the ultimate gateway to fully understanding your audience and fueling your email program. Whether your goal is to maintain a strong relationship with your audience or (in most cases) use your email program to increase your affiliate sales, understanding email marketing metrics as an affiliate is one of the most important skills you can learn.
Affiliate marketing metrics will help you craft the best possible strategy as an email affiliate, but that’s only if you’re able to fully understand them. To help you do just that, I’ll be going over the 16 most important email metrics for affiliate marketing to look at, how to measure the success of those metrics, and how to go about improving them (all based on my experience as an email marketing pro here at ClickBank!).
What Are Email Marketing Metrics and Statistics?
Before we dive into the metrics themselves, let’s first answer the question on everyone’s mind:
“What are email marketing metrics?”
Email metrics measure the performance of your email marketing campaigns, tell you how well your message is resonating with your audience, and show whether your campaigns are achieving their goals. Essentially, they allow you to objectively measure the success of an email campaign.
Email metrics can mean a multitude of different things based on what your goals are with each email, each campaign, or your entire email program.
Whether you realize it or not, some of the most common goals that you may have for your email program as an affiliate are to:
- Build trust with your audience
- Add an additional revenue stream to your existing affiliate channels
- Grow your overall profitability as an affiliate
- Provide useful information, education, or tools to help others reach their goals
Metrics can be broken down into the following categories:
Your email service provider (ESP) will provide you with an email metrics dashboard so you can accurately measure the performance of each individual email that you send.
But if you’re wondering how to improve email marketing metrics overall, you’ll need to look at patterns that form over time. This is how you get a better look at the overall context and impact of your affiliate marketing strategy.
If you’d like to get the most out of your marketing campaigns, we recommend forming your own goals by using the following email marketing metrics guide for affiliate marketing!
Key Engagement Metrics
Email Health Metrics
Performance Metrics
Google Postmaster Tools
5 Key Engagement Metrics
Diving right in, let’s talk about the top 5 key engagement metrics, from the open rate to the reply rate. Remember, engagement metrics are often set as key performance indicators (KPIs) that inform your progress relative to a business goal!
1) Open Rate
Open rate measures the percentage of people who opened your email. A high open rate typically suggests that you have an engaging subject line or a very engaged subscriber base.
Open Rate = (Total Emails Opened / Total Recipients) x 100
Open rates vary widely from niche to niche, and while you want to aim for them to be as high as possible, you should be happy to see open rates between 15-20%. This means that you’re targeting the right people with the right subject lines. If you’re consistently seeing lower open rates, that might be an indication of an issue with your subject lines, email deliverability, or audience engagement.
A/B testing affiliate emails with different subject lines can help you determine what’s getting your subscribers to open your emails, as well as what needs a bit of work. You can also look at data like which contacts interacted with your email campaign the most, the date the last email was opened, and the number of opens received from forwarded emails to help determine engagement levels and high-performing subject lines.
Open rate is one of the A/B testing metrics that can help you determine what resonates best with your audience and figure out what to optimize in your strategy. Other A/B testing metrics include click rate and click-through rate.
A quick aside: Open rates are being artificially inflated due to Apple Mail Privacy Protection (MPP) updates. Since June 2021, Apple has prevented email marketers from using invisible pixels to gather information from their subscribers. This hides information such as when and where an open takes place, the device the email was opened on, and any online activity taken on that device.
With these MPP updates for iOS 15 and above, Apple now preloads the content of emails, including the invisible tracking pixel, regardless of if the email is opened or not. This automatically reports that every email delivered to an Apple mail inbox has been opened. This means that anything that relies on open rate metrics, such as specific list segmentations or engagement rates, are no longer as reliable as they used to be.
This is not to say that open rates are “dead” – it just means that you need to rethink how you measure the success of your email program.
We recommend focusing on some of the other metrics listed in this article, such as conversion rate, overall ROI, and click rate. And, if you have specific goals in mind, pick out metrics from this article that support those goals!
2) Click Rate
Click rate is the percentage of people who clicked a link in your email out of all the people the email was successfully delivered to. This metric can help you determine whether your email is resonating with your readers or if your email is compelling enough to click through.
Click Rate = (Number of Unique Link Clicks / Number of Emails Delivered) x 100
Email metrics benchmarks say that a good click rate is typically considered to be anything of about 1% or above. A lower click rate could signal unclear or confusing calls to action (CTAs), an imbalance of CTAs, or that you’re sending irrelevant content or messaging to the wrong audience.
If you want to improve your click rate, study your audience and find out what captivates them, go through your emails and see what people have clicked on before, then compare that against the CTAs that people aren’t interacting with. Adjust your future CTAs accordingly.
Also, as a general tip, stick to one CTA per email to avoid any potential confusion that could lower your click rates.
3) Click-Through Rate
Click-through rate (CTR) measures the percentage of people who clicked a link in your email out of all the people who opened the email. It’s very similar to click rate, but it does not take external factors, like spam filters or unengaged contacts, into consideration. Click-through rate gives you a more focused look at the performance of the email itself, and helps you see just how many people are engaging with your emails and interested in learning more by clicking a link.
Click-Through Rate = (Number of Unique Link Clicks / Number of Emails Opened) x 100
The benchmark for an affiliate click-through rate is 3%, but don’t be discouraged if your metrics fall below that. Re-examine your audience to ensure that what you’re sending them actually aligns with their interests. Also, be sure to double check that your subject line accurately represents the email. Pulling a bait-and-switch with your audience could hurt both your click-through rate and your sender reputation.
As an affiliate, click rate and click-through rate may not be as important to your business goals as on-page traffic, conversion rates, or click-through rate on your affiliate page itself. The metrics you track will all depend on the goals of your specific business, emails, or campaigns.
A quick aside: Click-through rate is often considered to be interchangeable with either click rate or click to open rate. Some email service providers (ESPs) will ignore click rate and instead calculate click-through rate as the percentage of people who clicked a link in your email out of all the people the email was successfully delivered to. They will then calculate click to open rate as the percentage of people who clicked a link in your email out of all the people who opened the email. When evaluating your own metrics, just be sure that you understand exactly which definition your ESP is using.
4) Read Rate
Read rate calculates the percentage of people who opened and spent time reading your email. It helps you determine if your content is reaching and resonating with your audience, if your subject lines are attracting attention, and if your message and CTAs are being noticed.
| Read rate = (total number of real read / total emails delivered) x 100
Though similar to open rate, read rate takes into account the actual time that your email was kept open by a recipient. Your read rate will likely be less than your open rate, but you want to aim for it to be as close as possible. If you’re aiming for an open rate of around 20%, aim for a read rate of 15-20% or higher.
Whether or not an email has been “read” can be further broken down into the specific time spent viewing the email:
- Read: Contacts who have opened and viewed the email for 8 or more seconds
- Skimmed: Contacts who have opened and viewed the email for 2 – 8 seconds
- Glanced: Contacts who have opened and viewed the email for 0 – 2 seconds
Some email clients, like Gmail, do not offer access to this data. Keep in mind that this may artificially inflate your read rate.
5) Reply Rate
Reply rate, or response rate, is the percentage of your emails that receive a reply out of the total number sent. It helps you determine campaign effectiveness, as well as how well your emails are resonating with your audience.
Reply rate = (reponses / delivered emails) x 100
Your reply rate should ideally range between 1-10%, but the exact percentage may be more or less depending on the niche you’re in, the product you’re promoting, the audience you have, and type of email that you’re sending
Keep in mind that measuring reply rates is only important if your emails prompt a reply. This can happen if you’re asking a question or looking for specific feedback from your audience. If you open up your emails for replies, be sure to actively monitor the replies you receive, and plan to answer some. Also, be aware that you could receive both negative and positive comments from your audience.
Email Health Metrics
1) Email Delivery Rate
Email delivery rate is the percentage of emails that successfully get delivered to your recipient’s inbox. These emails have bypassed spam filters and ESP blockages while successfully passing all email filter checks like DKIM, DMARC, and SPF.
Delivery rate = ((number of emails sent – number of email bounces) / total number of emails sent) x 100
Ideally, email delivery rate for affiliates will be about 95% or higher. If it’s a bit lower at 90%, that could indicate a problem like a server issue on your recipient’s end of things. However, if it is much lower, we recommend investigating your sender reputation and DMARC records using Google Postmaster Tools. Being labeled as a spammer or having a low sender reputation will negatively impact your delivery rate.
If you are consistently seeing low delivery rates, that could mean that the big mailbox providers (Google, Yahoo, Apple) aren’t letting your emails get delivered to the inboxes of their users. This could happen due to high spam rates, bounce rates, unsubscribe rates, or other deliverability issues.
2) Deliverability
Email deliverability refers to the ability of your emails to bypass spam and promotional filters in order to successfully get delivered to the intended recipient’s inbox. As an email marketer, you can use your email’s deliverability rate to help predict the likelihood of your campaigns reaching your subscribers inboxes, which can then help you predict other email engagement metrics such as opens, clicks, and conversions.
Deliverability rate = (number of emails successfully delivered to the inbox / total number of emails sent) x 100
You should aim for the highest deliverability rate possible, ideally 85-95%. It is also important to recognize that you can have a fantastic delivery rate and a subpar deliverability rate, so we recommend implementing some deliverability best practices. Get DKIM, DMARC, and SPF set up, check your IP and Domain Reputation in Google Postmaster Tools, and always keep your DNS records updated.
- DKIM – Domainkeys Identified Mail. This creates a digital signature or watermark on an email that helps mailbox providers verify that the email is coming from who it says it’s coming from.
- SPF – Sender Policy Framework. A line of text that enables your domain to list 1. All the servers that emails are sent from and 2. The IP addresses that are allowed to send those emails. If an IP Address that isn’t on that list tries to send out an email, then the mailbox provider will block it.
- DMARC – Domain-based Message Authentication Reporting and Conformance. After an email recipient’s server checks DKIM and SPF, DMARC tells it what to do with the results: either allow the email in, quarantine it in spam, or reject it entirely. DMARC will also tell you which of your emails are passing or failing these checks, providing reports to help you identify any potential authentication issues or malicious activities.
- DNS Record – Domain Name System. A publicly available way to match web addresses to IP addresses. To set this up, you’ll need to contact your DNS provider or website hosting platform.
Maintaining proper list hygiene can also help your email deliverability. You do this by making sure you’re only sending to engaged and valid contacts and by regularly removing inactive, unengaged, outdated, or invalid contacts. You should also be segmenting your list based on engagement levels.
When you send to an engaged portion of your list, rather than the full list in its entirety, it can help reduce spam reports, improve key engagement metrics, and ensure that your message is getting heard. It also allows you to create more targeted promotional and re-engagement campaigns, ensuring that the right message gets delivered to the right people.
3) Bounce Rate
Bounce rate in email affiliate marketing is the percentage of emails that could not be successfully delivered to your recipient’s inbox. Emails can bounce for a wide range of reasons: subscriber engagement, technical difficulties, IP issues, authentication issues, invalid or non-existent email addresses, full inboxes, or other server issues.
Bounce rate = (number of bounced emails / total number of emails sent) x 100
Bounce rates should be 2% or less. If you’re consistently seeing a higher bounce rate, we recommend double checking that your DKIM, DMARC, and SPF are set up correctly, as well as authenticating and cleaning out your email lists.
4) Spam Complaint Rate
Spam complaint rate is the percentage of your email recipients who report your email as spam. This is a crucial metric that helps the email giants – Google, Apple, and Yahoo – determine your reputation as an email sender.
Spam complaint rate = (total number of emails marked as spam / total numbers of emails delivered) x 100
You want your spam complaint rate to be as low as possible, sitting at 0.1% or less. Consistently seeing a higher spam complaint rate could signal that you’re sending emails too often, that your emails are too aggressive in how they get people to click, or that they are untargeted for your audience.
Evaluate your email strategy and adjust accordingly so that your sender reputation (a score reflecting trustworthiness based on your sending habits, IP, and Domain Reputation provided by the email giants) isn’t tarnished.
We suggest focusing on sending real, valuable content, regularly clearing out unengaged contacts from your email list, and avoiding spammy or scammy marketing tactics.
Mailbox providers, internet service providers (ISPs), and anti-spam organizations often employ spam traps (or honeypots) to catch and identify senders who are sending unsolicited emails.
Spam traps can present as fake email addresses that have never been used by a real person, recycled domains or emails that were once valid, or addresses that contain common typos like ‘gnail’ or ‘aple.’ Spam traps are easy to avoid as long as you maintain proper list health and follow email best practices:
- Do Not Purchase Email Lists – Only email people who have properly consented to receive your emails.
- Validate the Emails on Your List – Implement email validation processes into your email list sign up forms to automatically check the legitimacy of email addresses that sign up.
- Implement a Double Opt-In Process – Ask recipients to confirm their email address before sending them anything. This helps ensure that your subscribers want your emails, as well as verifies that only legitimate recipients are on your list.
- Clean Your Email List – Get rid of subscribers who aren’t regularly engaging with your content. We recommend removing people who haven’t engaged with your content within half a year, but you can shorten or expand that timeline based on your sending schedule.
5) Unsubscribe Rate
Unsubscribe rate is a measurement of the percentage of people who opted out of your email campaigns. It helps you measure the health of your email list, as well as determine if the content that you’re sending is resonating with and providing value for your audience.
Unsubscribe rate = (total number of unsubscribes / total emails delivered) x 100
The benchmark unsubscribe rate for affiliate emails is 0.2-0.5%, but aim to keep your unsubscribe rate as low as possible. If you’re consistently seeing a higher unsubscribe rate, that may indicate issues with your email content, strategy, or list segmentation.
6) List Growth Rate
List growth rate, also called subscriber growth rate, shows how much your email list has grown over a given period of time, such as a quarter, month, or week. This metric helps indicate your email list hygiene, measures the effectiveness of your email strategy, and indicates the success of your email acquisition efforts.
List growth rate = ((new subscribers – unsubscribes) / total number of subscribers at the start of the period) x 100
On average, a mature email list will grow by about 1-3% per month. This means that the list is large, highly engaged, and highly relevant to the audience. If you’re seeing a slower growth rate, that might indicate an issue with lead generation, marketing effectiveness, or list churn. We recommend reviewing your overall email strategy, as well as your lead generation and targeting methods. You can try to add more subscribers on your email list by trying out the following email growth strategies:
- Effective Opt-In CTAs – Your CTAs on your signup forms should be clear and prompt action. Have it say something like ‘Join the Community’ or ‘Subscribe to My Newsletter’ to invite your website visitor to subscribe. Use words like ‘Get,’ ‘Download,’ or ‘Join’ since they prompt direct action.
- Lead Magnets – Offer valuable content like eBooks, discounts, or templates in exchange for an email subscription.
- Utilize Social Media – Promote your email list on your various social media platforms to encourage your followers to become your subscribers as well. You could provide social media subscribers with exclusive content, share snippets of your newsletter, or do a giveaway for your followers that subscribe to your email list.
- Optimize Your Website – Your landing pages should always contain an optimized and compelling email sign-up section, but we also suggest experimenting with popups and dedicated landing pages to turn visitors into subscribers as well.
- Double Opt-In – Implement a double-opt in email to ensure that your subscribers do in fact want to receive your content. This may actually lower the number of people subscribing to your list, but the people who confirm their interest are more likely to be highly engaged with your content. As an added plus, double opt-in processes can help protect you from fake emails and potential spam complaints.
If you’re just starting out, you might see a lower growth rate just because of how new you are to the space. Focus on finding new ways to build your list by sending engaging and valuable content.
Email list segmentation can also help improve engagement and subscriber retention. Segment your subscribers into smaller groups based on shared characteristics, such as engagement rates, demographics, interests, subscription sources, or purchase history. Subscriber segmentation will help you send more personalized and targeted emails, which may lead to higher engagement, attract more subscribers, and help to reduce email list churn.
Performance Metrics
The next group of metrics we should touch on are the performance metrics. These tell you how well specific channels and pages are contributing to your KPIs or sales goals!
1) Conversion Rate
In email marketing, conversion rate is the percentage of your email subscribers who completed a desired action after receiving your email message.
Conversion rate = (number of people who took the desired action / total number emails delivered) x 100
This action can be anything from following a social media account to purchasing your affiliate product. Arguably, conversion rate is one of the most important metrics in email marketing that you can track as an affiliate.
Why?
Well, the conversion rate is key for evaluating the effectiveness of your affiliate campaign, as well as refining your customer experience, but it doesn’t actually have a good baseline to go off of. The price of the product, the niche that you’re in, the size of your list, and the type of campaign that you run all make it difficult to provide one “average” across the board.
As an email marketer, it’s up to you to identify your own average conversion rate and compare it against your seller’s average conversion rate (if available). Once you have established a healthy conversion rate for your campaigns, you’ll want to consistently improve it over time!
This can be done through A/B testing, focusing on personalization, expanding on the value that the product provides, or targeting specific segments of your list.
The key to maximizing profitability as an email affiliate is to look at a combination of your average conversion rate and the average order value (AOV) of your campaigns.
Having a high conversion rate could appear to be a good thing, but if the product you’re selling is priced very low (making your AOV small), you could be missing out on an opportunity to sell a high priced product and drive a higher overall revenue from your campaign.
You might end up seeing your conversion rate drop, but the amount your audience is spending could increase. The key is to find the balance that creates the highest revenue output!
2) Email ROI
Return on investment (ROI) measures how profitable your email campaigns are, calculated by the affiliate email revenue generated for every dollar spent. Your ROI will help you see the effectiveness of your marketing campaign, determine where to allocate resources, and highlight any potential problems in your business.
ROI = ((total revenue generated – total cost) / total cost)
ROI varies heavily based on what you’re doing with your email list.
For email marketers, your overall email campaign ROI will average between $36 to $40 for every $1 you spend, but the exact number varies heavily based on industry, niche and product. In general, you can consider your overall ROI to be “good” if it ranges anywhere from $7 to $40.
While the numbers above refer to overall ROI, you can calculate ROI at a more granular level as well. Take a look at your campaigns and specific business goals to determine if you need to consider any of the following:
- ROI per campaign: Email campaign revenue in relation to the total cost to set up and run the campaign
- ROI per email: Revenue generated by an email in relation to the total cost of preparing the email
- ROI per subscriber: Email subscriber-generated revenue in relation to the total cost to acquire and maintain that subscriber
- ROI per hoplink: Revenue generated by affiliate tracking link performance
Email marketing is especially popular among affiliates because it tends to have a much higher average ROI than other marketing strategies.
You’ll really only be spending money on the transaction (a small fee charged by the payment processor) and your ESP, not each individual email or subscriber. So, it’s relatively cheap and can result in substantial returns if you do it right!
If you’d like to improve your ROI, we suggest using at least one of the following strategies:
- Automating your email campaigns.
- Writing effective and personalized subject lines and preview text.
- Regularly cleaning your email list.
- Committing to A/B testing your emails.
- Evaluating individual affiliate link performance.
- Experimenting with various email CTAs.
- Checking analytics, performance, and metrics.
- Adjusting and optimizing your campaigns based on past performance.
3) Cost Per Acquisition
Cost per acquisition (CPA) measures the average cost to acquire a new subscriber. It is often used to measure if a campaign or acquisition channel is financially efficient. CPA will show you how much you’re spending to add new subscribers to your email list.
CPA = Total amount spent / total subscribers acquired
It doesn’t actually require money to send an email like it does to run an ad. So, you won’t actually need to calculate CPA unless you are running any sort of paid ads. For instance, if you spent money on Facebook ads that pointed to an email opt-in lead magnet, you should calculate CPA by dividing the amount you spent by the subscribers you gained.
If you choose to track CPA in your email marketing, know that there is no set benchmark. You can see if your CPA can be considered “good” by looking at it in comparison to other metrics. In order for your CPA to be profitable, aim for it to be about three times smaller than your CLV.
4) Customer Lifetime Value
Customer lifetime value (CLV) measures the total amount of revenue that you can expect to gain from an email subscriber during their relationship with you. It is key to help affiliates understand the value of a subscriber, and can help you make decisions regarding email strategy and subscriber retention practices.
CLV = (average revenue per subscriber x gross margin) / churn rate
There is no set benchmark for CLV, as it varies greatly like most email metrics by industry. Common practice dictates that you aim for your CLV to be at least 3 times greater than the cost to acquire the subscriber in the first place.
Google Postmaster Tools
Your ESP should provide you with tracking data for most of the above metrics, but if you’d like to dive in even deeper, we recommend registering your domain with Google Postmaster tools.
You’ll just need to add a quick line of code to your DNS record, then you’ll be all set to check out how everything is performing on the backend.
Google Postmaster Tools is a game-changing free tool for affiliate marketers that allows you to accurately monitor and improve your email deliverability. It gives you a more in-depth view into how Google evaluates your emails, and provides data to help you help Google get your emails to the right place. It tracks the following:
- Spam Rate: The percentage of emails marked as spam by your email subscribers, not including emails sent directly to a spam folder.
- IP Reputation: The trustworthiness of your IP address, which can affect the likelihood an email will be delivered to the inbox instead of the spam folder.
- Domain Reputation: The trustworthiness of your domain, which can affect the filtering of an email into the inbox or spam folder.
- Feedback Loop: Provides information based on identifiers flagged by the Gmail Spam Feedback Loop (FBL).
- Authentication: The percentage of emails that have passed SPF, DKIM, and DMARC checks.
- Encryption: The percentage of encrypted inbound and outbound traffic.
- Delivery Errors: The percentage of emails that experienced rejection or failure as compared to all authenticated traffic.
Let Your Email Metrics Guide Your Action
That wraps up the 16 different email metrics to track as an affiliate marketer!
But, there’s one last thing you need to know: All of them are completely useless unless you’re using them to guide your email strategy.
The metrics that you track should be providing insights that you use to make positive changes and adjustments to your email strategy. Whether that means tracking metrics related to email performance, email list health, affiliate commissions, or overall business goals, you should always have a purpose in mind for each and every metric you track.
For example, if you’re seeing a low conversion rate on mobile, but a high conversion rate on desktop, that might mean that either your mobile emails aren’t optimized or that the affiliate product you’re selling is being considered too “big” of a purchase to be made on a phone.
Essentially, your job as an email marketer is to look at your metrics, identify any data that seems out of place, compare it to what you want to see, determine what’s causing an issue, and then implement changes to improve your campaign. The more you measure the success of your metrics, the better off you’ll be in the long-term.
So, what email marketing metrics will you be monitoring in your affiliate strategy?
NOTE: for a FULL list of affiliate marketing terms beyond just email metrics, don’t forget to visit our ultimate affiliate marketing glossary!
