Our first-time customers often have a lot to ask about our "unknown" result code. While every situation varies, we break down the commonly asked questions about this result group, below.
We often receive emails from customers who claim they received high bounce rate reports from their Email Service Provider (ESP), even after validating the email addresses on their lists with our service. This often occurs with customers who have not mailed to a specific list in a long time, or are new to an ESP. These customers will see messages from their ESP similar to "554 Reject by behavior spam" or "554 Spam violation." While it may seem like certain email addresses are labeled with these messages because they are invalid email addresses, that is actually not the case.