What are Deliverable, Non Deliverable, risky and Unknown contacts?

Deliverable Contact:  It is the type of contact in which the recipient’s email provider has confirmed that the email address exists and it is safe to send.

Undeliverable Contact: It is the type of contact where the address is either syntactically incorrect or does not exist.

Risky Contact: It is the type of contact in which the email address is of low quality and may result in a bounce or low engagement.

Unknown Contact: It is the type of contact in which we do not to receive a response from the email provider. Such verification will not be deducted from your credits balance.