B2B data accuracy: verification, bounce rates and data decay

A good email bounce rate for cold B2B email is under 2%. Smartlead's State of Cold Email 2026, built on more than 850 million emails sent through its platform, puts the typical sender at 1.54% and calls 2% the danger line. A quarter of senders bounce at 3.21% or higher.

Most of those bounces come from data decay. People change jobs, get promoted and leave their old mailbox behind. Companies get acquired and move to a new domain. A list that was clean the day you bought it turns into a list of dead addresses, and every bounce tells Gmail and Outlook that you don't check who you write to.

What is a good email bounce rate?

For cold outreach, use these as rules of thumb. The benchmarks behind them come from sending-tool vendors, so treat them as directional, not exact.

A bounce doesn't only cost you the one email. Mailbox providers watch the error rate on your domain. Google's email sender guidelines tell senders whose messages "start bouncing or start being deferred" to cut volume until the error rate drops, and to automatically unsubscribe recipients with multiple bounced messages. Microsoft rejects mail from domains sending 5,000 or more messages to its consumer services unless SPF, DKIM and DMARC all pass (Microsoft Support).

So a bad list and a weak sending setup stack. Fix both.

Hard bounce vs soft bounce

Every bounce comes back with an SMTP reply code, and the first digit tells you which kind it is. RFC 5321, the standard that defines how email is delivered, splits failed deliveries into two classes.

Hard bounce (5xx): permanent. The most common one is 550, "mailbox unavailable": the address doesn't exist, access is denied, or the server rejected the message on policy grounds. The standard says the sender should not repeat the same request.

Soft bounce (4xx): temporary. The mailbox is full (452, "insufficient system storage"), the server is busy, or it's shutting down (421). The RFC's rule of thumb is that a 4xx reply could succeed if you try again without changing anything.

What to do with each:

• Remove a hard bounce from every sequence the same day, and mark it in your CRM so nobody imports it again next quarter.
• Let your sending tool retry soft bounces. If the same address soft-bounces on three sends in a row, treat it as a hard bounce.
• Read the text after a 550. "User unknown" means the person is gone. A rejection that mentions authentication, reputation or policy means the problem is your setup, not your list.

Why B2B data decays

The US Bureau of Labor Statistics reports that the median worker had been with their current employer for 4.1 years in January 2026. For workers aged 25 to 34, it was 3.0 years (BLS, Employee Tenure in 2026). Those are medians, so this is rough math. But it means a real share of any contact list will work somewhere else within a year, and their old work email will start bouncing once IT closes the mailbox.

Job changes aren't the only cause:

• Promotions and title changes. The email still works, but your "Head of Demand Gen" is now VP Marketing and your message no longer fits.
• Domain changes. Acquisitions and rebrands move whole companies to a new domain. The old addresses forward for a while, then stop.
• Companies closing or shrinking. The domain stops accepting mail.
• Mail server changes. A company moves providers or turns on catch-all, and what a verifier can see changes overnight.

So treat every list as a snapshot. It's most accurate on the day it was checked and a little worse every week after. When a vendor tells you their data is accurate, the useful follow-up question is: checked when?

Accuracy also has a legal side. GDPR's accuracy principle says personal data must be "accurate and, where necessary, kept up to date" (GDPR Article 5). Emailing people who left a company two years ago is a deliverability problem and a compliance one. The B2B data compliance guide covers the rest.

Catch-all emails: why no verifier can confirm them

A catch-all domain (also called accept-all) accepts mail for any address at that domain, whatever comes before the @. Companies set it up so mail to a misspelled name doesn't get lost. The side effect: when a verifier asks the server whether jane.doe@company.com exists, the server says yes. It says yes to xq7z@company.com too.

Some catch-all addresses are real and land fine. Some vanish without a bounce. Some bounce hours later, when the server sorts its queue. From the outside, you can't tell which is which.

How to handle them:

• Keep catch-all addresses in their own segment, separate from verified ones.
• Send to them in small batches and watch the bounce rate for that segment on its own.
• For your highest-priority contacts on catch-all domains, start on LinkedIn or the phone and use email second.
• If a catch-all domain bounces, stop sending to every address on that domain.

How email verification works

Verification tests an address without sending it an email. A typical check runs in layers:

1. Syntax. Is it a valid address format?
2. Domain and MX records. Does the domain exist, and does it have a mail server?
3. Mailbox check. The verifier starts an SMTP conversation with that mail server, asks whether it would accept mail for the address, and disconnects before anything is sent.
4. Catch-all detection. It also asks about an address that can't exist. If the server accepts that one too, the domain is catch-all.
5. Risk flags. Role addresses like info@ or sales@, disposable domains and free webmail.

What verification can't do is predict the future. An address that passed in January can bounce in April. Some servers delay or refuse verification checks, which leaves the result as "unknown". And a valid mailbox says nothing about whether the person still holds the title in your CRM.

The practical rule is to verify close to the send. If a list has sat for more than a month or two, check it again before a large campaign.

Email bounce rate vs website bounce rate

If you searched "is a 70% bounce rate good", you probably meant your website, and that's a different metric. In Google Analytics 4, bounce rate is the percentage of sessions that weren't engaged. A session counts as engaged if it lasts longer than 10 seconds, has a key event, or has two or more page views (Google Analytics Help).

A website bounce rate of 50% can be normal for a blog. An email bounce rate of 5% means the list is broken.

How to keep your bounce rate low

• Verify every address shortly before you send, and re-verify anything older than a month or two.
• Put catch-all and "unknown" results in their own segment.
• Remove hard bounces after every send and sync that back to your CRM.
• Authenticate every sending domain with SPF, DKIM and DMARC. Google requires all three for senders of more than 5,000 messages a day to Gmail accounts.
• Ramp new sending domains slowly and spread volume across inboxes.
• Treat "she's no longer with the company" replies as data. Update the record and ask who took over.
• Track bounce rate by list source. If one source bounces at 4% and another at 1%, you know which data to trust.

If you're deciding where your data should come from in the first place, B2B lead lists: build vs buy walks through what to check before you pay for a list. And once it's clean, outbound to in-market accounts covers how to work it.

How AdsGTM keeps list data accurate

AdsGTM builds every list from Contactlevel's own data: 1.2 billion business contacts worldwide, with the deepest coverage in North America, then the EU and UK. Contact records refresh every 14 days. Intent signals refresh every 24 hours and can be backfilled up to 14 days.

Every work email is checked with an email verifier before delivery. Catch-all domains accept any address, so no verifier can fully confirm them, and we mark them so you can decide how to send.

Your list is checked at delivery. From that day it ages like any other list, so order a refresh when your market changes or before a big push. A refresh is $1,000. The fields you get, and how each one is used, are in what's in your list. Pricing is on the homepage.

One honest caveat: your bounce rate depends on your sending setup as well as the list. We don't publish a bounce guarantee, and you should be wary of anyone who does.