# Why Results Can Differ Between Tools

It is normal for email verification results to differ between tools.

Email verification is not an exact science.

***

### Email Servers Do Not Behave Consistently

Email verification relies on how recipient servers respond.

Those responses can change based on:

* Time of day
* Sender IP reputation
* Connection limits
* Security policies
* Temporary server states

Two tools can test the same email and receive different responses.

***

### Catch-All Domains Are the Biggest Variable

Many business domains are configured as catch-all.

This means:

* The server accepts all emails
* Valid and invalid addresses appear identical
* Basic SMTP checks cannot distinguish them

Some tools label all catch-alls as risky.

CSVgo runs additional validation steps to reduce uncertainty, but some variability will always remain.

***

### Security Gateways Affect Results

Modern email systems use:

* Secure Email Gateways (SEGs)
* Advanced routing rules
* Conditional Non-Delivery Reports

These systems may:

* Accept emails but drop them later
* Reject verification probes but accept real sends
* Hide mailbox existence by design

Different tools interpret these signals differently.

***

### Verification Depth Varies by Tool

Not all tools perform the same checks.

Differences may include:

* Number of verification signals used
* How aggressively retries are handled
* How greylisting is interpreted
* How false positives are filtered

CSVgo combines multiple signals instead of relying on a single test.

***

### Real-World Sending Is the Final Test

Verification predicts deliverability.\
It does not guarantee it.

Actual results depend on:

* Your sending infrastructure
* Domain age and reputation
* Warm-up status
* Copy and offer
* Sending volume and pacing

This is why testing is always recommended.

***

### Why CSVgo May Show More Deliverable Emails

CSVgo often returns:

* Higher deliverable counts
* Fewer emails stuck in “risky”

This happens because:

* Catch-alls are validated instead of discarded
* ESP behavior is considered
* Multiple verification signals are combined

More data does not mean more risk when used correctly.

***

### How to Interpret Differences Safely

Best practice:

* Start with conservative exports
* Test in controlled batches
* Observe bounce and reply rates
* Adjust ESP segmentation over time

CSVgo gives you options so you can choose your risk level.

***

### Key Takeaway

Differences between tools are expected.

What matters is:

* Transparency
* Accuracy over time
* Control over what you send

CSVgo is built to give you better inputs and let you decide how to act on them.