Are outgoing emails in Zendesk encrypted to end users?
Zendesk Support and Zendesk Chat have opportunistic support for Transport Layer Security (TLS), a cryptographic protocol for email exchanges. This feature is enabled automatically on every account. Emails are encrypted whenever an inbox provider supports encrypted messages. It is not possible to have a forced TLS connection. If the receiving server does not support TLS encryption then ESMTP is used instead.
For more information on Zendesk’s security features, see this page: Secure customer service.