Learn how CSVgo verifies email addresses by checking syntax, domains, SMTP responses, and server behavior to classify emails as valid, invalid, or catch-all.
In this step, CSVgo determines whether each email address is:
Valid
Invalid
Catch-all (unknown or risky at this stage)
This step focuses on technical deliverability, not assumptions or guessing.
What Email Verification Does
CSVgo performs a deep email verification process designed to reduce bounces and protect sender reputation.
Each email is evaluated using multiple technical checks to determine whether the address can receive email.
Verification Checks Performed
Duplicate Removal
Before verification begins, duplicate email addresses are removed automatically.
This prevents:
Wasted verification credits
Duplicate outreach
Inflated list sizes
Email Syntax Check
CSVgo checks that each email:
Uses valid characters
Contains a proper local part
Includes an @ symbol
Has a correctly structured domain
Invalid syntax results in immediate classification as invalid.
Domain and DNS Check
CSVgo verifies that the email domain:
Exists
Has valid DNS records
Is configured to receive email
Domains without valid mail records are marked as invalid.
SMTP Connection Test
CSVgo attempts to establish a connection with the recipient’s mail server.
The server response is used to determine whether:
The mailbox exists
The mailbox does not exist
The server accepts all addresses (catch-all behavior)
This step is critical for real-world deliverability assessment.
Greylisting and Retry Logic
Some mail servers temporarily reject verification attempts and require retries.
CSVgo accounts for this behavior by:
Detecting soft responses
Retrying verification automatically
Avoiding premature invalid classifications
Catch-All Detection
If a mail server accepts messages for non-existent addresses, the domain is marked as catch-all.
At this stage:
The email is neither confirmed valid nor invalid
It is classified as catch-all (risky or unknown)
These emails move to the next verification step.
Disposable and Free Provider Detection
CSVgo detects whether an email address belongs to:
Disposable or temporary email providers
Free email services such as Gmail or Outlook
This information is stored for segmentation and campaign strategy decisions.
Role-Based Email Detection
CSVgo identifies role-based addresses such as:
info@
admin@
support@
sales@
These emails are flagged so teams can decide whether to include or exclude them.
Verification Results at This Stage
After Step 4, every email is categorized as one of the following:
Valid – confirmed to exist and receive email
Invalid – confirmed not deliverable
Catch-all – server accepts mail but mailbox existence is unknown
Catch-all emails are not discarded. They proceed to the next verification step.
Why This Step Matters
Email verification:
Reduces hard bounces
Protects domain reputation
Improves inbox placement
Creates a clean foundation for advanced verification
This step ensures only technically deliverable emails continue in the workflow.
Summary
In Step 4, CSVgo:
Removes duplicate emails
Checks syntax and domains
Connects to recipient mail servers
Identifies valid, invalid, and catch-all emails
Prepares catch-alls for deeper verification
The next step focuses specifically on catch-all verification to recover additional deliverable leads.