Email deliverability feels like a mysterious art. Authentication records, IP warming, engagement algorithms. But the biggest factor in whether your emails reach inboxes isn't technical configuration. It's whether you're sending to real, active email addresses.
Send to bad addresses, and you get bounces. Bounces hurt your sender reputation. Reputation drops, and email providers start sending you to spam. Spam means lower engagement. Lower engagement further hurts reputation. The spiral continues until your email program is barely functional.
The root cause isn't your email platform or your content. It's your contact data.
How Bad Data Kills Deliverability
Email providers (Gmail, Microsoft, Yahoo) track sender behavior. They're looking for signals that you're a legitimate sender versus a spammer. Data quality issues send all the wrong signals.
Hard Bounces
A hard bounce means the email address doesn't exist. The mailbox was never real, or it was deleted when someone left a company. Either way, the message can't be delivered.
Email providers track bounce rates. High bounces indicate you're sending to lists you haven't maintained, which is spammer behavior. A bounce rate over 2% is a yellow flag. Over 5% is a red flag that can trigger spam filtering across your entire sending domain.
Spam Traps
Spam traps are email addresses designed to catch senders with bad practices. Two main types:
Recycled spam traps: Old email addresses that were abandoned, then reactivated by email providers to catch senders who don't clean their lists. If you're emailing someone who left their company three years ago, that address might be a trap now.
Pristine spam traps: Addresses that were never used by a real person, planted in places where only scrapers would find them. Hit these and you're flagged instantly.
Spam traps don't bounce. They receive your email silently and report you to blocklists. You won't know you hit one until your deliverability craters.
Disengaged Contacts
Email providers measure engagement. If you keep sending to people who never open, never click, and never reply, you look like a sender that recipients don't want to hear from.
That database of 50,000 contacts you've built over five years? If 30% haven't engaged in two years, they're actively hurting your deliverability. Every non-open signals to Gmail that your emails aren't wanted.
Role-Based Addresses
Addresses like info@, sales@, support@ often go to shared inboxes or get filtered. They have lower engagement rates and sometimes aren't monitored by anyone. High volumes of role-based addresses in your sends can drag down your metrics.
Diagnosing the Problem
Before fixing anything, understand where your data quality actually stands.
Check Your Bounce Rates
Pull bounce reports from your email platform. Look at:
- Hard bounce rate (permanent failures)
- Soft bounce rate (temporary failures, but repeated soft bounces often indicate problems)
- Bounce rate trends over time (getting better or worse?)
- Bounce rate by list segment (is one source particularly bad?)
Healthy hard bounce rate: under 0.5%. Acceptable: under 2%. Problematic: over 2%. Emergency: over 5%.
Analyze Engagement Decay
Create segments based on last engagement date:
- Engaged in last 30 days
- Engaged in last 90 days
- Engaged in last 12 months
- No engagement in 12+ months
What percentage of your list falls into each bucket? If over 25% of your "active" email list hasn't engaged in a year, that segment is hurting you.
Audit Recent Imports
List imports are the most common source of bad data. For each import in the last year:
- What was the source?
- Was it validated before upload?
- What's the engagement rate from that import?
- What's the bounce rate?
You might find that one event list or purchased list is responsible for a disproportionate share of your deliverability problems.
Check for Known-Bad Patterns
Search your contact database for:
- Obvious fakes ([email protected], [email protected])
- Disposable email domains (mailinator, guerrillamail, etc.)
- Your own domain (employees who shouldn't be in marketing lists)
- Competitor domains (if you're B2B and they shouldn't be getting your content)
Cleaning Your Data
The goal is a list where every address is real, active, and interested.
Remove Known Invalids
Start with the easy wins:
Hard bounces: Remove anyone who has hard bounced. There's no reason to keep them on an email list. Most platforms do this automatically, but verify it's working.
Unsubscribes: Remove or suppress anyone who has unsubscribed. Obvious, but check that your suppression lists are actually being applied to all sends.
Spam complaints: Remove anyone who has marked your email as spam. Continuing to email them is both futile and damaging.
Validate Your List
Run your email list through a validation service. Options include ZeroBounce, NeverBounce, Kickbox, and others. They check whether addresses:
- Exist and can receive email
- Are known spam traps
- Are temporary/disposable addresses
- Are role-based addresses
Remove or suppress addresses flagged as invalid. Consider suppressing risky addresses (catch-all domains, role-based) from your main sends.
For CRM-specific guidance: Email Validation in Salesforce | Email Validation in HubSpot
Sunset Disengaged Contacts
Contacts who haven't engaged in 12+ months are unlikely to start. They're hurting your deliverability by dragging down engagement rates.
Options:
Sunsetting campaign: Send a "still interested?" campaign to disengaged contacts. Those who respond stay on the list. Those who don't get removed.
Suppression: Move long-term disengaged contacts to a suppressed segment. Don't delete them (they might have value for sales), but stop emailing them.
Reduced frequency: If you're not ready to fully remove them, at least reduce send frequency to this segment. Monthly instead of weekly. Quarterly instead of monthly.
Segment by Engagement
Not everyone should get every email. Create segments based on engagement level:
- Highly engaged: Opened or clicked in last 30 days. Send frequently.
- Moderately engaged: Engaged in last 90 days. Send regularly.
- Lightly engaged: Engaged in last 12 months. Send selectively.
- Dormant: No engagement in 12+ months. Send rarely or not at all.
Sending your best content to your most engaged contacts improves metrics. Good metrics improve reputation. Reputation improves deliverability for everyone.
Preventing Future Problems
Cleaning your list is a project. Keeping it clean is a process.
Validate Before Import
Never import a list without validating it first. This is especially critical for:
- Event lists
- Purchased/rented lists (if you use them at all)
- Partner-provided lists
- Historical data from CRM migrations
Make this a policy. No validation, no import.
Double Opt-In for High-Risk Sources
For sources where data quality is uncertain, use double opt-in. The contact submits their email, receives a confirmation email, and must click to confirm. This ensures the address is real and the person actually wants your emails.
Double opt-in reduces list growth, but the contacts you get are genuinely interested. Quality over quantity.
Automated Bounce Handling
Configure your email platform to automatically suppress hard bounces after one occurrence. For soft bounces, suppress after 3-5 consecutive failures.
Re-Engagement Automation
Set up workflows that automatically move contacts to low-engagement segments when they haven't engaged in X days. Trigger re-engagement campaigns. Move to suppressed if re-engagement fails.
This catches disengagement before it becomes a deliverability problem.
Regular Validation
Email data decays. People change jobs, companies change domains, mailboxes get abandoned. Re-validate your list quarterly, or at minimum semi-annually.
The Numbers That Matter
Track these metrics to monitor data quality impact on deliverability:
Hard bounce rate: Should be under 0.5%. Above 2% is a problem.
Spam complaint rate: Should be under 0.1%. Above 0.3% is a problem.
List decay rate: What percentage of addresses become invalid per month? Track over time.
Engagement by segment: Are engaged contacts staying engaged? Is disengagement accelerating?
Inbox placement: If you use a deliverability monitoring tool, track inbox vs. spam placement rates.
When these numbers drift in the wrong direction, data quality is usually the cause.
Common Questions
What bounce rate is too high?
Industry standard is under 2% hard bounce rate. Above 2% signals a data quality problem. Above 5% is serious and can damage your sender reputation. If you're consistently above 2%, clean your list.
Why are my emails going to spam suddenly?
Email providers track sending patterns and engagement. If you're sending to lots of invalid addresses or addresses that never engage, your reputation drops. Poor reputation means more emails go to spam, even to valid addresses.
How often should I clean my list?
Validate new imports before uploading. Re-validate your full list quarterly. Email data decays at roughly 25-30% per year. Annual cleaning isn't enough.
Deliverability suffering because of dirty contact data?
Clean My Email ListRelated: Salesforce Email Validation | HubSpot Email Validation | Finding Missing Emails