What are B2B cold email deliverability rates? Belkins’ 2026 study

We tracked every bounce and unsubscribe across 7.5 million cold emails. Here’s what the data says about deliverability health in the B2B sector.

When an email doesn’t reach the inbox, everything downstream falls apart — no read, no reply, no meeting. Deliverability is the foundation on which the rest of your outreach is built on.

We analyzed 7,530,489 cold emails sent across Belkins client campaigns from January through December 2025. We tracked two signals that together define deliverability health: bounce rate (emails that never reached the recipient) and unsubscribe rate (recipients who actively opted out). The data spans more than 40 industries and 70 countries.

Here’s what we found.

Key takeaways

• The overall B2B cold email bounce rate in 2025 was 1.71%, implying a deliverability rate of 98.29% — a healthy baseline by industry standards.
• Bounce rates are significantly higher in the first half of the year. H1 averaged 1.93% versus 1.45% in H2 — a 25% improvement as the year progressed.
• May is the worst month for deliverability, with a peak bounce rate of 2.26%. October is the best at 1.26%.
• Geography matters. India (3.26%) and Spain (2.86%) have the highest bounce rates among major markets, while Finland (0.71%) and Sweden (1.05%) have the lowest.
• The average unsubscribe rate was 0.36% — low, but with a notable spike in September (0.46%) and a sharp drop in December (0.26%).
• Advertising & Marketing sees the highest unsubscribe pressure at 0.70%. Insurance, at 0.15%, is among the most receptive audiences in the dataset.

What does deliverability actually mean in cold email?

Deliverability is a broad concept, and it’s worth defining what we’re measuring before diving into the data.

In a strictly technical sense, deliverability refers to whether an email reaches the recipient’s mail server at all. Still, in practice, it’s best thought of as deliverability health — a combination of signals that tell you how much of your outreach is actually getting through and whether it’s landing well or creating problems for your sender reputation.

We track two core metrics for this:

Bounce rate is the percentage of sent emails that were rejected by the recipient’s mail server and never delivered. A hard bounce typically means the email address doesn’t exist or the domain is inactive. A soft bounce means a temporary issue — a full inbox, a server timeout, etc. Both count in our data. High bounce rates directly hurt your sender reputation and can trigger spam filtering across your entire sending domain.

Unsubscribe rate is the percentage of recipients who clicked “Unsubscribe” after receiving your email. While technically the email was delivered, a high unsubscribe rate signals that the audience isn’t receptive, which has downstream effects: email providers notice when people consistently opt out of your messages, and it feeds into their filtering decisions.

Together, these two metrics give a clear picture of deliverability health.

What is the email deliverability rate in B2B?

Across all 7.5 million emails in our 2025 dataset, 128,605 bounced — giving an overall bounce rate of 1.71% and an implied deliverability rate of 98.29%.

This is a strong baseline. Industry guidance generally treats anything below 2% as acceptable and under 5% as manageable. Our data sits comfortably under that 2% threshold in aggregate.

That said, the aggregate hides real variation across months, geographies, and industries. The sections below unpack where that variation lives and what it means for planning your outreach.

How bounce rates change throughout the year

The monthly data tells a clear story: the first half of the year is consistently harder on deliverability than the second.

H1 average: 1.93% — H2 average: 1.45%

That’s a 25% improvement from the first half to the second. The pattern isn’t random. A few factors likely drive it:

Q1–Q2 brings stale lists. Many companies launch or restart their outbound programs at the beginning of the year, often using contact lists that were built or last cleaned the previous year. Email addresses go stale at a rate of roughly 20–25% annually through role changes, company exits, and domain deprecations. The longer a list has been sitting, the more bounces it will generate when activated.

Summer and fall list hygiene improves. By the time H2 rolls around, teams have burned through their most problematic contacts, and ongoing campaigns have already surfaced and suppressed bad addresses. The list is cleaner simply because it’s been used.

The December uptick (1.61%) is worth watching. After a run of low bounce rates from September through November, December sees a partial reversal. The end-of-year holiday season, expired company domains, and a general slowdown in email server activity across organizations likely contribute to this shift.

Bounce rates of B2B emails by country

Geography turns out to be one of the more meaningful predictors of bounce rate in our data. We’ve filtered to countries with at least 4,000 emails sent to give reliable numbers.

What drives these differences?

The Nordic countries (Finland, Sweden, Norway, Denmark average: 1.42%) generally show some of the cleanest deliverability in Europe, with Finland as the standout at under 1%. This aligns with the high organizational stability and strong corporate email hygiene practices in these markets.

The contrast within Europe is notable. While Scandinavia performs well, southern European markets such as Spain (2.86%) and Italy (1.69%) are higher. France at 1.90% and Germany at 1.62% sit in the middle of the range.

India (3.26%) and Mexico (3.16%) topping the table likely reflects a combination of higher staff turnover rates in fast-growing businesses and contact lists that may include more SMB-tier companies where email churn is faster.

The United States — which accounts for 74.6% of all emails in this dataset — sits at 1.72%, just above the overall average of 1.71%.

B2B email unsubscribe rate benchmarks

Across all 7.5 million emails, 27,335 unsubscribe events were recorded — an overall rate of 0.36% per email sent.

This figure is low by most benchmarks. For comparison, Mailchimp and Campaign Monitor typically report unsubscribe rates of 0.2–0.5% for permission-based email marketing. That cold outreach lands in the same range is a positive signal about targeting quality and messaging relevance across Belkins campaigns.

How unsubscribe rates change throughout the year

Two patterns stand out:

The September–October spike. The unsubscribe rate peaks in September (0.46%) and remains elevated in October (0.44%). This is the period when Q3 pipeline pressure peaks and sales teams across industries intensify their outreach. Inboxes fill up. Decision-makers who have been largely absent over the summer return to find a backlog of cold messages and are more likely to take the definitive step of unsubscribing than to ignore them.

The December low. December sees the sharpest drop of the year, down to 0.26%. Fewer people are actively managing their inboxes, and the cadence of cold outreach drops across the board, reducing the friction that triggers unsubscribes.

Unsubscribe rates by industry

Industry is the most actionable dimension here. Unsubscribe rate reflects audience receptivity — how willing a given vertical is to hear from cold outreach, at a population level.

Advertising & Marketing (0.70%) leads the table by a significant margin — nearly 3× higher than Insurance at the bottom. This is consistent with what you’d expect: marketing professionals receive a high volume of cold outreach, are more sensitized to it, and are more likely to manage their inboxes actively. Reaching this audience requires messaging that stands out immediately.

Food & Beverage (0.59%) and Industrial Machinery (0.50%) are both notably high, which is less intuitive. In Food & Beverage, the audience skews toward regional operators and smaller chains where decision-makers are often time-pressed and have lower patience for outreach that doesn’t immediately address their operational reality. Industrial Machinery’s elevated rate likely reflects niche buyers who are infrequently targeted but highly specific in what they’ll engage with.

The lower half of the table — Insurance (0.15%), Biotechnology (0.21%), Retail (0.22%) — represents audiences with stronger tolerance for cold outreach, whether because they’re accustomed to vendor relationships, operate in sales-heavy cultures themselves, or receive lower volumes of outreach relative to other verticals.

Reading bounce and unsubscribe together

Bounce rate and unsubscribe rate measure different failure modes, but they compound. A contact who bounces is gone from your list. A contact who unsubscribes is also gone — but they’ve also generated a negative signal that email providers record.

Looking at both together gives the fullest picture of deliverability health across the year:

May is the highest-risk month for deliverability health overall — combining the peak bounce rate with continued unsubscribe pressure. May campaigns are working against the highest signal loss in the dataset.

October and November are the cleanest months, with the lowest combined signal loss. This makes Q4 an underrated window for cold outreach from a pure deliverability standpoint — and it aligns with the broader strategic argument for Q4 outreach that many sales teams overlook in favour of end-of-year pipeline pressure.

What these benchmarks mean for your outreach

A few actionable conclusions from the full picture:

Set the right baseline expectation. A bounce rate under 2% is healthy. If your campaigns are running above that, the problem is almost always list quality rather than messaging. Email address verification before sending is the most direct lever for correcting it.

Time your list refresh before H1. Given that Q1–Q2 show consistently higher bounce rates, investing in verification and re-validation of your contact database before January is disproportionately effective. A clean list entering the year prevents sender reputation damage that’s difficult to recover from mid-campaign.

Adjust your expectations by market. If you’re targeting India, Spain, or France, build in a higher expected bounce rate and consider more aggressive list hygiene for those segments. If your primary markets are Northern European, your baseline should be considerably cleaner than the overall average.

In high-unsubscribe industries, tighten your targeting. Advertising & Marketing, Food & Beverage, and Industrial Machinery audiences are telling you they find most outreach irrelevant. The answer isn’t to stop sending — it’s to be more precise about who you reach and why your message is relevant to them specifically.

Don’t treat September as your safest launch window. Despite having low bounce rates in that month, September sees the year’s highest unsubscribe rate. The audience is back at their desks and actively filtering. That’s a context that rewards relevance, not volume.

📚 For channel-specific benchmarks, see our companion studies:

• Sales follow-up statistics in B2B
• The best time to send cold B2B emails
• What are B2B cold email response rates?

This study is based on 7,530,489 cold emails sent through Belkins client campaigns between January and December 2025, spanning more than 40 industries and 70 countries. Bounce rate is calculated as bounced emails divided by total emails sent. Unsubscribe rate is calculated as the number of unsubscribe events divided by the total number of emails sent.