Reply checks each email address by different parameters to classify it into 3 groups. Once the validation is done, we assign different statuses based on the results: Valid, Risky, and Invalid.
Valid
A green icon next to the contact's email indicates the address is safe and valid. The verification has been completed and no high-risk factors have been detected. Valid emails are safe to put into the sequences.
Here is what the Valid status looks like if you hover over the icon:
Risky
The Risky status means the recipient's mail server stated the recipient exists but may still result in a bounce, or is of low value. We recommend treating the Risky status as Valid. The best practice is to add up to 20% of Risky emails to avoid high bounce rates.
Here are the reasons the email is marked as Risky:
Domain is a well-known DEA (disposable e-mail address provider).
Catch all - the external mail exchanger accepts fake and non-existent e-mail addresses, so the email may not exist / we cannot verify its existence.
Honeypot - the external mail exchanger hides a honeypot/spam trap.
Invalid
The last status you can see is the Invalid one. The contacts with invalid statuses do not receive your sequence emails.
💡 Important: A contact with an Invalid status can be moved in a sequence only if there are no email steps. This covers API as well.
The email address is considered invalid if the response has one of the following errors:
Syntax errors
A quoted-pair within a quoted word is not closed properly.
An unexpected quoted-pair sequence has been found within a quoted word.
A new word boundary start has been detected at an invalid position.
An invalid character has been detected in the provided sequence.
The number of parentheses used to open comments is not equal to the one used to close them.
An invalid sequence of two adjacent dots has been found.
The local part of the e-mail address has an invalid length.
An invalid folding white space (FWS) sequence has been found.
The at-sign symbol (@), used to separate the local part from the domain part of the address, has not been found.
An invalid quoted word with no content has been found.
The email address has an invalid total length.
The domain part of the email address is not compliant with the IETF standards.
DNS errors
The domain of the e-mail address does not exist.
The email address's domain does not have any valid DNS records and couldn't accept messages from another host on the Internet.
Mailbox errors
The mailbox for the e-mail address does not exist.
The external mail exchanger refused to accept messages.
The external mail exchanger does not support international mailbox names, while the supplied address pretends to have one.