The metrics of an email outreach campaign: the ones that matter and the ones to ignore

Outreach tools display dozens of numbers. Most are interesting, few are useful for deciding anything. An email outreach campaign is steered with a handful of metrics, read in the right order and on a sufficient volume. The rest mostly serves to reassure.

The metric to forget: open rate

For years, emails were judged on their open rate. It was measured with a tiny invisible image loaded when the message was opened. That mechanism no longer works properly:

• since 2021, Apple Mail preloads the images of every incoming message, which makes emails nobody has read show up as "opened";
• many business email clients block images by default, which makes genuinely real opens disappear;
• some security filters open messages to analyse them before delivering them.

The result: open rate is both inflated and underestimated, depending on the recipient. It can help spot a gross anomaly (zero opens across an entire campaign usually signals a deliverability problem), but not to compare two subject lines or two messages.

The main metric: positive replies

What matters is the number of people who reply with a real interest. Calculate it against the number of people contacted, not the number of emails sent (one person receives several emails in a sequence).

The overall response rate is useful, but it mixes everything together: interest, refusals, out-of-office replies, unsubscribe requests. A campaign that generates a lot of irritated replies has an excellent response rate and a very poor result. So look at:

• the overall response rate;
• the share of positive replies within that total;
• the number of meetings booked per hundred people contacted.

That last figure is the most telling when deciding whether a campaign is worth continuing or expanding.

The safety check: bounce rate

The bounce rate measures the share of emails that come back as errors because the address doesn't exist or won't accept messages. It's an indicator of list quality, but also of risk: a high rate quickly damages the reputation of your mailboxes.

• under 2%: healthy list;
• between 2 and 5%: list to clean before expanding;
• above 5%: stop the campaign, clean the list and look for the source of the problem.

SmartOutbound automatically pauses a campaign above 5% bounces, as soon as it has reached a volume large enough for the figure to mean anything.

The hidden metric: inbox placement

You can't know directly whether your campaign emails land in the inbox or in spam at your prospects'. But your warmup mailboxes measure it continuously: every message exchanged in the network is found at its recipient, in the inbox or in spam.

This rate is the best indicator of the health of your mailboxes. Above 90%, all is well. Below 80% for more than a week, the mailbox needs to come out of campaigns while you work out why. Our article on deliverability lists the most common causes.

Unsubscribes and complaints

A low, stable unsubscribe rate is normal in outreach. A sudden rise signals poorer targeting or a message that landed badly. Complaints ("mark as spam") are more serious and harder to measure, because email clients don't always pass them on to the sender. If you start seeing irritated replies, assume there are silent complaints behind them.

Clicks and conversions

If your follow-ups contain a link (to a case study, a demo page), the click rate gives an indication of interest, with one caveat: some security filters click on links to check them, which generates false clicks.

More useful still, if your website records sign-ups or contact requests, you can tie those conversions back to the prospects in your campaigns. SmartOutbound does this with a small script to install on your site: it attributes a sign-up to the prospect who made it, or to a colleague at the same company. That's the measurement closest to revenue.

Read the numbers by step and by variant

A campaign breaks down into steps (first email, follow-ups) and sometimes into variants (several subject lines tested). Look at the replies obtained at each step:

• if most replies come on the first follow-up, its angle may deserve to move to the front;
• if the last follow-up no longer produces anything positive, delete it;
• if one subject line gets clearly more replies than another on a sufficient volume, keep it.

For subject lines, SmartOutbound automatically splits the sends and gradually favours the variant that gets the most replies, without waiting for the end of the campaign.

From when is a number reliable?

It's the most common mistake: concluding too early. With 50 people contacted, two replies more or fewer shift the response rate by four points. A few reference points:

• fewer than 100 people contacted: look at the replies one by one, not the percentages;
• between 100 and 300: strong trends become visible;
• above 300: you can compare variants with reasonable confidence.

Also wait for the end of the sequence before judging a campaign: a significant share of replies come on the follow-ups, sometimes two to three weeks after the first email.

The minimal dashboard

If you were to track only five numbers:

1. the number of meetings per hundred people contacted;
2. the share of positive replies;
3. the bounce rate;
4. the inbox placement rate measured by warmup;
5. the unsubscribe rate, to detect a targeting problem.

The rest is useful for understanding, not for deciding. For an overview of the method, reread our guide to B2B email outreach. And to get these numbers without a spreadsheet, try SmartOutbound free for a month.