# Step 6: Email Service Provider Identification

After verification and catch-all analysis, CSVgo identifies the **email service provider (ESP)** for every deliverable email address.

This step classifies emails into:

* **Google**
* **Outlook**
* **Other providers**

ESP identification happens automatically as part of the same workflow. No external tools are required.

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### Why Email Service Provider Identification Matters

Email deliverability and reply rates are strongly influenced by the recipient’s email provider.

Different providers:

* Filter emails differently
* Apply different spam rules
* React differently to volume, copy, and sending patterns

Treating all providers the same often leads to:

* Lower inbox placement
* Reduced reply rates
* Burned sender reputation

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### How CSVgo Identifies ESPs

CSVgo analyzes domain-level and MX-level signals to determine which provider handles incoming mail for each address.

This allows CSVgo to reliably group emails into:

* Google-hosted inboxes
* Outlook and Microsoft-hosted inboxes
* Other providers (custom servers, regional hosts, or legacy setups)

The result is a fully segmented list without manual lookups.

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### Common Use Cases

#### ESP-Specific Campaigns

You can run separate campaigns for:

* Google-only inboxes
* Outlook-only inboxes
* Other providers

This allows you to tailor:

* Copy
* Volume
* Warm-up strategy
* Sending schedule

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#### Excluding Outlook Temporarily

Many outbound teams choose to:

* Delay sending to Outlook inboxes
* Exclude Outlook during early warm-up phases
* Send to Outlook with lower volume or different infrastructure

CSVgo enables this instantly without additional tooling.

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### Proven Impact on Reply Rates

Segmenting or excluding certain ESPs has been shown to:

* Improve inbox placement
* Reduce spam filtering
* Increase reply rates by **2–3x or more**

Results depend on:

* Sending infrastructure
* Domain age
* Volume
* Copy quality

ESP identification gives you the control needed to optimize these variables.

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### No External Tools Required

Without CSVgo, ESP identification typically requires:

* Additional paid tools
* Manual domain checks
* Spreadsheet work
* Multiple exports and imports

CSVgo performs ESP identification automatically as part of the same processing flow.

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### Summary

In Step 6, CSVgo:

* Identifies Google, Outlook, and other email providers
* Segments inboxes automatically
* Enables ESP-specific outreach strategies
* Removes the need for external ESP detection tools

After this step, your list is fully verified, segmented, and ready for analytics and export.