dovecot as proxy and verification of the backends certificate

[Heiko Schlittermann]

Hello,

I'm using a dovecot as proxy, connecting to one or more backends.
The backends use X.509 certificates.

The proxy's passdb returns

    extra fields:
    user=foo
    proxy
    host=backend1.<domain>
    ssl=yes
    nopassword=y

Thus the proxy connects to the backend but can't verify the backends
certificate. 

The following comment suggests using ssl_client_ca_file for that.

    # Directory and/or file for trusted SSL CA certificates. These are used only
    # when Dovecot needs to act as an SSL client (e.g. imapc backend). The
    # directory is usually /etc/ssl/certs in Debian-based systems and the file is
    # /etc/pki/tls/cert.pem in RedHat-based systems.
    #ssl_client_ca_dir = 
    #ssl_client_ca_file =
    ssl_client_ca_file = /tmp/certs/ca-local.pem

But that does not work! Instead I've to use  ssl_ca

    # PEM encoded trusted certificate authority. Set this only if you intend to use
    # ssl_verify_client_cert=yes. The file should contain the CA certificate(s)
    # followed by the matching CRL(s). (e.g. ssl_ca = </etc/ssl/certs/ca.pem)
    # ssl_ca = 
    ssl_ca = </tmp/certs/ca-local.pem

Bug or feature? Mainly I'm asking because the comments do not indicate
that I should have used ssl_ca for this type of operation (dovecot as a
SSL client)

    Best regards from Dresden/Germany
    Viele Grüße aus Dresden
    Heiko Schlittermann
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