The importance of email list validation can't be exaggerated. But it’s often missed by businesses and individuals that go in for email marketing.
What does email validation mean? It's a process that verifies whether or not an email address is deliverable and valid. That is when you send an email message to a recipient, the message is actually delivered and does not bounce because of the invalid user.
Some marketers don't think bounce emails are a serious problem. However, it is. The primary reason why you should validate your email list is because the bounce rate directly affects your sender reputation.