Messages sent through Envoke are encrypted in transit between Envoke's SMTP sending servers and the destination SMTP servers using TLS (Transport Layer Security) encryption.

The final segment of the message journey from the destination SMTP server to the recipient's email client can only be encrypted if a private encryption key has been exchanged with the email client for every contact in your database. This is why end-to-end encryption such as S/MIME is typically used for one-to-one messages or messages exchanges within working groups.

End-to-end encryption is not feasible for broadcast email services, which includes Envoke (see Wikipedia "End-to-end encryption" article).
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