In this article you’ll find:
What is a "bounce"?
In the world of email outreach and marketing, a bounce happens when you send an email but it cannot be delivered to the recipient’s inbox. Bounces generally fall into two categories:
Hard bounce: This is a permanent failure, for example, the email address doesn’t exist, the domain is invalid, or the recipient’s mail server says "no such user".
Soft bounce: This is a temporary failure, perhaps the mailbox is full, the server is down, there’s a transient routing issue, or the domain is valid but the recipient server temporarily rejects it.
If you’re seeing more bounces than you expected it means many of your emails are being rejected or cannot be delivered, despite the quality of the data provider.
Why a bounce can occur
There are many reasons why an email may bounce. Below are some of the common causes, and how they relate to data providers and your own process.
Invalid or non-existent addresses
If the email list includes outdated contacts, misspellings, or addresses that no longer exist (someone changed jobs, the company shut down, the domain expired), you’ll get hard bounces. Even when a provider claims "95% accuracy", that may refer to the state of verification at a point in time, but addresses can become invalid afterwards.
Mailbox issues
Even if the address is valid, the recipient’s mailbox might be full, inactive, or temporarily unreachable, resulting in a soft bounce.
Domain or MX record problems
If the domain of the recipient’s address has no valid MX (Mail Exchange) record, or is mis-configured, then delivery fails. Even if the user exists, the domain may refuse mail or bounce it.
Recipient server policies / spam filters
The recipient’s mail server might enforce strict policies: rejecting unknown senders, filtering out messages from low-reputation IPs, grey-listing, or rejecting messages that fail authentication. These can trigger bounce-like behaviour or "blocked" deliveries.
"Accuracy" claims vs real-world delivery
When a data vendor such as UpLead claims "95% data accuracy" (e.g., valid emails), that is a measure of data quality at point of verification. It does not guarantee zero bounces when you send email, because your sender reputation, the recipient server, list hygiene, content, timing, all play a part.
List purchase, cold outreach, unverified lists
If you’re using lists obtained from third-party sources, or haven’t verified them recently, you increase your risk of invalid addresses. If you send to many addresses that are invalid, your bounce rate will go up, and that may trigger blocking or deliverability issues.
How a sender can become blocked
Getting bounces is not just a metric problem, it can affect your sending reputation, which in turn can get you blocked by mail servers. Here's how that can happen:
If you send to many invalid addresses (hard bounces), recipient domains and ISP filters may flag your sending domain or IP as "low quality" or "spammy" so you need to choose your data provider carefully and ensure they are giving you only valid emails.
If you also send to un-engaged or non-opted-in recipients, you may get high complaint rates or low engagement, which again hurts your reputation.
If you send large volumes to new recipients without "warming up" your domain/IP, you may trigger rate limits or grey-listing from major providers.
If your domain lacks proper authentication (SPF, DKIM, DMARC) or is found on blacklists, recipient servers may outright reject or block your messages.
Once your reputation is poor, even valid addresses may bounce or be diverted to spam, so your bounce rate goes up, which further damages reputation in a vicious cycle.
In short: a high bounce rate can lead to blocking, and blocking will make even good addresses fail.
How to avoid high bounce rates (and maximise the value of UpLead)
The good news: you can take effective steps to reduce bounce rates, protect your sender reputation, and ensure your outreach works, and using UpLead correctly plays a big part. Below is a best-practice checklist.
1. Use a high-quality data provider (like UpLead)
With UpLead:
You get access to 175 M+ leads, verified in real time.
UpLead guarantees "95% data accuracy or higher" at the point of download.
Every email you download is verified before export, reducing invalid addresses.
Using such data helps reduce the number of invalid addresses you send to, which guarantees a strong start.
2. Re-verify existing lists before sending
Even if your list comes from elsewhere, verify each email just before sending (or use the built-in verification features of Uplead ). UpLead’s email verification features catch invalid addresses in real time.
Remove or suppress addresses flagged as "invalid", "catch-all but risky", or "accept-all but unknown".
3. Segment and warm up your sending domain/IP
If you’re sending from a new domain or IP, start small. Send to your most engaged, known contacts first.
Gradually increase volume over days/weeks.
Monitor bounce rates, complaints, and engagement. If you spike bounces, stop sending and investigate.
For cold outreach, start with smaller campaigns (e.g., 50-100 per day) before scaling.
4. Set up proper authentication and maintain reputation
Ensure SPF, DKIM, and DMARC records are correctly configured for your sending domain.
Watch for any blacklisting or negative feedback.
Avoid "spammy" content, excessive links, attachments, or misleading subject lines.
Use a dedicated sending IP/domain if possible for cold outreach.
5. Monitor bounce/feedback and clean lists constantly
Track hard vs soft bounces. Remove addresses that hard bounce immediately.
If an address soft-bounces repeatedly, suppress it.
Monitor complaint rate (spam reports) and unsubscribe rate.
Clean inactive addresses (e.g., no opens or clicks in last 6-12 months), even if they don’t bounce, low engagement harms reputation.
6. Target the right audience and personalise content
With UpLead’s advanced filters (+50 filters) you can build lists matching your ideal customer profile: job title, technology used, company size, location.
Use this to send relevant, personalised content, high relevance leads to better engagement, fewer bounces/complaints, and stronger reputation.
Segment by engagement level: treat warm leads differently from cold ones.
7. Use UpLead’s built-in tools for best results
When using UpLead, you benefit from real-time email verification at the moment of download/export, which means you pay only for verified emails.
Combine list building with enrichment: fill missing data, verify direct dials, enrich company data to personalise outreach better.
Use UpLead’s export and integration with your CRM so lists stay organised and duplication or outdated records are avoided.
Summary
Seeing more bounces than expected despite a "95% accuracy" claim is a sign you need to look beyond just the data provider. A bounce is simply a failed delivery (hard or soft), and many factors beyond address validity impact it, including your sender reputation, list hygiene, content, authentication, and deliverability setup.
By using a high-quality provider like UpLead, re-verifying lists, warming your domain/IP, authenticating properly, cleaning lists, targeting well and personalising, you’ll significantly reduce bounce rates and protect your outreach reputation.
Next Steps
Still need help? Contact UpLead Support for further assistance.