Sometimes, the ISP or the recipient’s anti-spam program may erroneously reject a legitimate message or filter it as spam. This is a case of a false positive.
False Positive is a term associated with email validation. It describes a situation where an email address is wrongly identified as deliverable or valid, i.e., being defined as good when it is actually not.
Marketers and senders are at severe risks with false positives, considering how much damage sending messages to a bad email address can do to their sender’s reputation. In severe cases, it may lead to blacklisting.
This is why it is important to identify email addresses correctly before sending out emails.