Many businesses invest heavily in content, templates, and segmentation—but unknowingly sabotage their deliverability through hidden infrastructure mistakes. These issues often go unnoticed because they don’t produce instant errors. Instead, they quietly lower trust, reduce inbox placement, and create long-term deliverability problems that are hard to fix later.
This article explains the most common infrastructure mistakes that silently damage email performance and how to avoid them.
Using Suboptimal Domains
Your domain is one of the strongest deliverability signals. Poor domain choices can make your emails look untrustworthy, even if your content is perfect.
Common Domain Mistakes
- Using your main domain for all email traffic (marketing + transactional + internal).
- Relying on very new domains with no sending history.
- Using unclear or unrelated subdomains that make ISPs suspicious.
- Sending from free email domains instead of your own branded domain.
Better Practices
- Use separate subdomains for different email types:
- marketing.yourcompany.com
- notify.yourcompany.com
- billing.yourcompany.com
- Maintain a clean, consistent sending history.
- Keep domain authentication (SPF, DKIM, DMARC) configured and monitored.
Relying on Unstable Shared IPs
Shared IPs are widely used, but they have risks when the pool isn’t well-managed.
Issues That Quietly Harm Deliverability
- Another sender on the IP hits a blacklist.
- A spam incident from one user damages the entire IP reputation.
- Unpredictable sending behavior across the shared pool creates trust issues for ISPs.
When Shared IP Is Fine
- Your email volume is low or irregular.
- Your provider maintains a highly controlled shared environment.
When It Becomes a Problem
- You send high-volume campaigns.
- You need stable, long-term deliverability.
- You need full control over your sender reputation.
Irregular Email Volume Patterns
ISPs watch your sending patterns closely. Sudden changes signal potential risk.
Harmful Patterns
1. Massive spikes (e.g., 20x your normal volume).
2. Sudden drops that break consistency.
3. Irregular campaign schedules with no predictable pattern.
4. Long periods of silence followed by a huge blast.
These patterns often look like suspicious behavior, similar to compromised accounts or spam campaigns.
How to Fix Volume Issues
1. Set a predictable schedule.
2. Warm up new domains or IPs gradually.
3. Avoid “big blast” campaigns; break them into batches.
4. Maintain steady baseline traffic.
Lack of Infrastructure Monitoring
Deliverability suffers when the system is not monitored and issues go unnoticed.
Silent Problems You Might Miss
- Domain authentication fails without warning.
- IP reputation drops gradually.
- DNS configuration changes break email setups.
- Bounce and complaint rates rise without being addressed.
- Blacklists detect your sending pattern but you don’t see the alert.
Essential Monitoring Areas
- Authentication health (SPF, DKIM, DMARC).
- Bounce and complaint trends.
- IP and domain reputation scores.
- Blacklist status.
- Open and click patterns.
- Spam folder rates.
Poor List Hygiene Infrastructure
List hygiene is not only about removing invalid contacts. It’s also about the systems that support healthy email sending.
Infrastructure Failures
- Outdated suppression lists.
- No automated removal of hard bounces.
- Duplicate entries across multiple systems.
- No re-engagement or sunset policy for inactive users.
- Storing old contacts that haven’t interacted in years.
Impact
These problems trigger more bounces, complaints, and negative signals—hurting deliverability silently over time.
Misconfigured Authentication
Authentication is one of the core pillars of email trust. Small misconfigurations can cause big damage.
Common Mistakes
- SPF records exceeding lookup limits.
- DKIM keys that are too weak (1024-bit or lower).
- DMARC set to “none” indefinitely.
- Multiple systems sending from the same domain without alignment.
- Overlapping or conflicting DNS records.
Why This Is Dangerous
Without correct authentication, ISPs may treat your emails as unsafe or spoofed—even if sent legitimately.
Building Stronger Email Foundations
Email deliverability is not just about content—it’s about trust. And trust is built on infrastructure.
Fixing small hidden issues like domain setup, volume patterns, and monitoring can dramatically improve inbox placement. When your technical foundation is clean, stable, and predictable, ISPs are far more likely to reward your emails with better deliverability.
By focusing on these infrastructure fundamentals, businesses can improve the reliability of their email operations and ensure their messages consistently reach the inbox.