Before anyone replies to an email, they first have to open it. Understanding what the open rate is helps you measure the first step: what percentage of recipients in an email campaign actually open the message, regardless of what they do next.

The common mistake is to look at this metric in isolation, as if a high open rate were synonymous with a successful campaign. An email can be opened frequently and generate zero replies, indicating that the problem is not in capturing initial attention, but in what happens after that open.

In this guide, we explain what the open rate is, how it is calculated, and specifically what the sales open rate is—the use of this metric applied to B2B outbound prospecting campaigns.

What is the open rate and how is it calculated

The open rate is the percentage of recipients who open an email, calculated over the total number of emails that actually reached the inbox. It is calculated by dividing the number of recorded opens by the number of delivered emails, and multiplying that result by 100.

For example, if 200 emails are sent and 60 people open them, the open rate is 30%. This metric says nothing about what happened after the open: whether the person replied, ignored the message, or deleted it immediately.

What is a good open rate in B2B email marketing

In B2B outbound prospecting (cold email) campaigns, an open rate between 40% and 60% is typically considered solid, provided the list is well-targeted and clean. In newsletter campaigns to an existing subscriber base, benchmarks are usually different and generally lower, between 15% and 25%.

Comparing the open rate of an outbound campaign with that of a generic newsletter makes little sense: the audiences, objectives, and segmentation levels are completely different.

Factors that most influence the open rate

• The email subject line. This is the factor with the greatest direct impact: a generic or clearly promotional subject line significantly reduces the open rate.

• The sender's name. A real person's name usually generates more opens than a generic company name.

• The time and day of sending. Sending at times when the recipient is likely actively checking their inbox improves the probability of an open.

• The technical reputation of the sending domain. Authentication issues can prevent the email from even reaching the primary inbox, affecting the open rate before the content even matters.

Common mistakes that lower the open rate

• Using subject lines that sound like spam. Exclamation marks, excessive capitalization, or words like "free" trigger filters and suspicion.

• Sending from a new domain without warming it up. A newly configured domain, without a history of gradual sending, usually suffers from poorer deliverability at the beginning.

• Not cleaning the contact list. Invalid or inactive addresses damage the domain's reputation and lower the overall open rate.

• Repeating the same subject line throughout the sequence. This reduces curiosity and the likelihood of opens on follow-up emails.

How to improve the open rate without sounding like spam

• Write short and specific subject lines. Mentioning something concrete about the company or the recipient's role performs better than a generic subject line.

• Warm up the domain before sending high volume. Gradually increasing the volume of sent emails helps build technical reputation.

• Segment and clean the list regularly. A smaller but highly targeted list usually yields a better open rate than a large, generic list.

• Vary the subject lines in each email of the sequence. This prevents the recipient from immediately recognizing it as an automated follow-up.

SalesDose: how we structure outbound prospecting email sequences

A high open rate that does not translate into replies typically indicates that the problem lies not in capturing initial attention, but in the message that follows after that open.

To acquire qualified leads, we must address both parts: the technical reputation and subject line that secure the open, and the message content that converts that open into a real reply.

If your outbound campaigns have strong open rates but do not generate replies, speak with our team.

Frequently asked questions about the open rate

These are the most common questions from B2B sales teams regarding email open rates.

What exactly is the sales open rate?

It is the exact same open rate calculation, applied specifically to outbound prospecting (cold email) campaigns, rather than internal communications or newsletters.

Is the open rate a reliable metric today?

Less so on its own, because some email clients pre-load content and register opens that are not real. Therefore, it is best to analyze it alongside other metrics, such as response rate, rather than in isolation.

How often should the open rate be reviewed?

Weekly during an active campaign, in order to quickly detect if a certain subject line or segment is underperforming and adjust before continuing to send the same message.

Is a low open rate always the fault of the subject line?

Not always. It can also be caused by technical deliverability issues, such as the domain being flagged as suspicious, in which case the email will not even reach the primary inbox, regardless of how good the subject line is.

Is it advisable to send the same email to the entire list to compare the open rate?

It is better to split the list into segments and test subject line variations in parallel. Comparing results between similar segments provides more reliable insights than testing a single change at a time across the entire list.

The open rate is the first step of a well-executed sales outsourcing strategy, not the final objective. A campaign that opens well but fails to generate replies still has work pending on the message, not the subject line.

Are your outbound campaigns opening well but generating no replies? Let's review them together →