What is greylisting technology and why does verification take time

Greylisting is a highly efficient anti-spam technology used to protect email users from spam. 

While verifying emails with greylisting technology turned on, it’s impossible to perform verification instantly. Recipient mail servers don’t accept any incoming emails at the first shot, telling the sending server to resend their messages again within the specified time. A well-configured mail server will try to resend an email at different intervals until it’s accepted or rejected by the receiving mail server.

Snov.io uses breakthrough anti-greylisting technology when we face any greylisting. We wait for some time and verify such emails on the second try. The waiting time may vary from a minute to an hour. Although this process takes more time than usual, this increases the number of valid emails you will receive back from us, so the results won’t upset you. 

While verifying emails, you will see the following message if the email is greylisted: 


While finding emails, you will see the following message which means that this email needs a bit more time to go through the greylisting technology. 


Note that the waiting time doesn’t depend on the number of greylisted emails. You may upload 1 or 100,000 emails for verification, the time delay will be the same. 

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