Transport Layer Security (TLS) provides additional data security for IMAP. The TLS protocol provides communications security over the Internet and allows client and server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. The TLS protocol is based on the SSLv3 protocol but provides improved data security.

For more information about TLS, go to About Transport Layer Security (TLS).

The IMAP Proxy supports both implicit and explicit TLS. In the IMAP proxy action, the TLS settings are for implicit TLS and the STARTTLS settings are for explicit TLS. For information about how to configure explicit TLS in the IMAP proxy, go to IMAP-Proxy: STARTTLS.

You can enable both implicit and explicit TLS encryption in the same IMAP proxy action, but each connection uses only one encryption method. Connections on port 993 use implicit TLS encryption (IMAPS) and connections on port 143 use explicit TLS encryption (STARTTLS).

TLS for the IMAP-proxy is supported in Fireware OS v12.1 and higher.

To enable TLS support in the IMAP-proxy policy, you must enable content inspection in the proxy action.

About Certificates for TLS Encryption

When content inspection is enabled, the proxy action uses a certificate when it re-encrypts the traffic after inspection.

  • For inbound traffic, the proxy action uses the default Proxy Server certificate.
  • For outbound traffic, the proxy action uses the Proxy Authority certificate.

For more information about these certificates, go to About Certificates.

Change the TLS Support Option in the IMAP Proxy Policy

To enable content inspection in the IMAP proxy action, TLS Support must also be Enabled or Required in the IMAP-proxy policy.

In the IMAP proxy policy, you can set TLS Support to one of these options:

  • Disabled — IMAP proxy listens on port 143 only
  • Enabled — IMAP proxy listens on ports 143 and 993 (default)
  • Required — IMAP proxy listens on port 993 only

Enable Content Inspection in the IMAP Proxy Action

To enable content inspection in the IMAP-proxy, you must select the Inspect action in the TLS settings for the proxy action used by your IMAP-proxy policy. When you select the Inspect action, the proxy uses the settings in the TLS profile for content inspection. You can edit the TLS profile settings in the proxy action, or from the TLS Profiles page.

See Policy TLS Settings

For a proxy policy to perform content inspection, the TLS Support option in the proxy policy must be set to Enabled or Required. If you edit the TLS settings in a proxy action from the Proxy Actions list, the proxy action could apply to more than one policy. After you enable content inspection, make sure that TLS Support is set to Enabled or Required in all policies that use the proxy action.

To see the TLS Support setting for all policies that use the proxy action:

  1. Edit the proxy action from the Proxy Actions list.
  2. In the proxy action TLS settings, click View.
    A list of policies that use the proxy action appears, with the TLS Support setting for each policy.


Related Topics

Configure TLS Profiles

About the IMAP-Proxy

About Proxy Actions