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Outbound Selling

5 Advanced Outbound Email KPIs to Track for Cold Prospecting

How do you track, measure, and improve the performance of an outbound email campaign?

When asked, there are usually three common email metrics that come to mind:

  1. Open Rate
  2. Click-Through Rate (CTR)
  3. Reply/Response Rate

While it’s good to track all three, these basic metrics are limited in how much information they can reveal about email messaging, prospect behavior, or outcomes.

To help make it easier to improve cold email performance, here are five more advanced email metrics to track for deeper insights, clearer data analysis, and better testing.

1) Open Rate vs Open Frequency

Open rates are a popular email marketing metric, but there is a lot of ambiguity around how to track and interpret email opens for performance improvement.

Some sales engagement software provides open rates based on the total number of prospects that open any email in a campaign, regardless of when, where, or how many touches it took.

Others show open rates for a specific step or version within the journey, which doesn’t provide big picture insights but helps test specific parts of an outbound email sequence.

Both of these perspectives on open rate offer important context about performance. However, it’s often hard to bring these different data sets together to identify clear engagement patterns.

A powerful way to gain clarity on email opens is by tracking average frequency.

How many total times does a prospect open emails throughout their outbound journey? How many opens does a specific email generate per send?

Email open frequency provides a deeper look at prospect behavior by differentiating between a single open, multiple opens, and multiple opened emails.

While it’s common for prospects to open a cold email once without responding, frequent opens or multiple opens in a short time period can indicate potential interest for a conversation.

2) Tracking Outbound Email Metrics After an Open

Responses and click-throughs are key metrics to track for outbound email marketing.

To calculate the basic reply rate and click-through rate of a campaign, divide the number of unique email replies or clicks by the total number of prospects in the sequence.

Easy, right?

However, these metrics don’t show the full picture of engagement levels. Before a prospect can respond or click-through on an email, they must first open it.

Unfortunately, many factors impact email opens that are difficult to control. Email Service Providers (ESPs), email deliverability, or simply a busy inbox can reduce open rates.

One way to measure cold email performance with more accuracy is to track engagement metrics once prospects have opened an email.

Here are a few examples based on common prospect behaviors.

Open-to-Click Rate (Click-Through Rate / Open Rate) – The open-to-click rate tracks the percentage of prospects who click-through on a link after opening an email.

Open-to-Reply Rate (Reply Rate / Open Rate) – The open-to-reply rate tracks the percentage of prospects who respond to an email after it’s opened.

Open-to-Unsubscribe Rate (Unsubscribe Rate / Open Rate) – The open-to-unsubscribe rate tracks the percentage of prospects who request removal or Do Not Contact after opening.

Open-to-Ignore Rate (“No Action” Rate / Open Rate) – The open-to-ignore rate tracks the percentage of prospects who do not take a measurable action after opening an email.

Together, these metrics show the underlying activity patterns of prospects after an email open.

Whether a prospect unsubscribes, takes action, or chooses to ignore the message, these behaviors hold more significance after an opened email compared to a potentially sent email.

3) Inbound Conversion Rates on Email Clicks

Inbound vs outbound sales is a common debate in the B2B world.

In reality, both methodologies complement each other and work hand-in-hand to create better sales experiences. Outbound outreach can generate opportunities for inbound leads.

Email click-throughs indicate potential interest but don’t show anything meaningful about what happens after prospects click.

If 20 prospects click on a link after receiving email outreach, how does the website’s experience effectively convert them into inbound opportunities?

To make the most of outbound email, it’s important to track the outcomes of every click-through and design inbound acquisition channels to align with an outbound campaign.

With targeted landing pages, sales & marketing teams can personalize the website experience for outbound prospects to maximize the chances a click-through becomes an inbound lead.

4) Outbound Email Reply Sentiment

While reply rates are a popular way to measure the performance of an outbound email campaign, not every email response has the same value.

Some prospects respond to a cold email with genuine interest or curiosity. Others ask blunt questions, request information, raise objections, or reject a conversation entirely.

Some even react unproductively, unprofessionally, or request to unsubscribe from the outreach.

Quantitative metrics like response rates only show parts of the full story, so it’s important to gauge the quality of replies when evaluating outbound email performance.

To gain more clarity into the value of email responses, organize replies into different qualitative categories based on the prospect’s sentiment or intent.

For example, any actionable reply with momentum to become a sales opportunity could be considered a “positive” response.

Replies from prospects that aren’t in-market or have no interest could be in a category for “neutral” responses. Unsubscribes could be considered “negative” responses.

By tracking response quality, it’s easier to measure the impact of email replies and identify patterns that consistently generate positive response outcomes.

5) Response Times for Outbound Leads

Both inbound and outbound conversations are time-sensitive, so salespeople often compete for opportunities with responsiveness and speed.

A study from InsideSales found that response times for calling inbound leads greatly impacted the odds of both contacting and generating qualified opportunities:

  • A 10-minute response time was 4 times less likely to qualify versus 5 minutes
  • The odds of contacting a lead were 10 times lower after the first hour
  • After 20 hours, additional outreach actually hurt the chances of making contact

Response times make a huge difference for inbound leads, so it’s even more important to be responsive in cold conversations with outbound leads.

In addition, phone and email are very different sales channels. If the chances of contact decrease with time for calling, it’s likely that emails are also affected by response speed.

By tracking response times, teams can identify ways to accelerate the process and make outbound email marketing more effective for starting conversations.


Cold email is still an effective way to start sales conversations.

Email might provide less control than a live phone call, but it gives sales teams access to the power of automation, scalability, and measurability.

While there is no perfect formula or solution for outbound email in every situation, the right KPIs and testing can help continuously improve selling outcomes.

With these five advanced email metrics, sales & marketing teams can gain deeper visibility into outreach performance and identify winning changes to drive long-term success with email.

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