Here is an explanation of what are accept-all and unknown validation statuses and how to handle them.
Catch-All
Catch-All, also known as accept-all, refers to a domain-wide setting on a mail server that accepts all emails sent to that domain, regardless of whether the specific mailbox exists or not. This can be a common practice in small businesses or larger organizations to ensure that they receive any emails sent to them, even if there are typos in the recipient’s address. However, it is important to note that email validation services cannot accurately determine the validity of these emails. As a result, accept-all emails are considered risky.
Unknown
On the other hand, the status “Unknown – Unreachable” refers to situations where the email server is not reachable or verifiable by the validation service. This could be due to various reasons, such as the sensitivity of the email server blocking validation IPs or temporary network issues.